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Hello all,
Recently I have had a major issue with my nexus 7. About a week ago, it died (ran out of battery) while I was using it. When I attempted to turn it on after charging it, I would get the screen that says google, with unlocked lock icon. The tablet would be frozen at this screen. I left it running until it died again. I was running the latest stable release of cyanogenmod 10 with no problems before when this happened.
By now I had realized that the nexus may have been bricked. I did some googling and found that this is an issue other users have been having when their battery died on android 4.2.2. I attempted to restore the nexus. At this time I was able to access bootloader on the device by holding down all of the buttons at the same time. However, I decided not to restore the nexus, and wait until a time where I would be able to turn all of my attention to the problem. But when I tried to restore the device yesterday, I was not able to access bootloader! I connected the device to my PC (running win8) and it is not recognized. Similarly, trying fastboot restart-bootloader gives me "waiting for device". I am afraid that the bootloader may have been corrupted somehow.
My question is, how can I fix this? Is there a way to reflash the bootloader, or is there something that I am missing? Is there a hardware operation that needs to be performed on the device (battery pull, etc)?
Thanks.
AW: [Q] Help! Nexus 7 not working, may be bricked
I doubt your nexus is bricked. Most likely you entered the APX mode. Hold down the power button for about 6-10 seconds, then it should exit from there.
http://forum.xda-developers.com/wiki/APX_mode
Sent from my Nexus 7 using xda app-developers app
Not working
AndDiSa said:
I doubt your nexus is bricked. Most likely you entered the APX mode. Hold down the power button for about 6-10 seconds, then it should exit from there.
http://forum.xda-developers.com/wiki/APX_mode
Sent from my Nexus 7 using xda app-developers app
Click to expand...
Click to collapse
When I hold down the power button, the device just turns off and comes back on again. The google boot logo shows for a few seconds, then I get a black screen.
patil215 said:
When I hold down the power button, the device just turns off and comes back on again. The google boot logo shows for a few seconds, then I get a black screen.
Click to expand...
Click to collapse
If you get a Google logo, that is a good sign - it means the bootloader is at least partially intact, possibly even in perfect shape.
I would proceed assuming that your battery is completely discharged.
Put the device on the charger overnight and then try starting it up while it is still plugged in to the charger. Hold the vol-down button and the power button continuously until at least one second after the Google logo flashes - this should put the device into fastboot mode if the bootloader is intact.
Something to remember is that Li-Ion batteries have a safety feature that prevents them from charging if the battery voltage gets too low. This is part of the reason why they are shipped with a 50% charge - they can sit that way for months and months only self-discharging at a very very slow rate.
OTOH, if you discharge the battery deeply and then let it sit for a long time afterward - especially if there is something like APX mode draining current - the battery voltage can fall below this "safety threshold voltage" and (even though it is still a "good battery" it can no longer be charged).
I'm not sure it the N7 can be started up while plugged in to only the charger; if it can, disconnecting the battery and trying to power up the device might be a way to discriminate "dead device" from "unchargeable battery".
good luck
I've tried this before
bftb0 said:
If you get a Google logo, that is a good sign - it means the bootloader is at least partially intact, possibly even in perfect shape.
I would proceed assuming that your battery is completely discharged.
Put the device on the charger overnight and then try starting it up while it is still plugged in to the charger. Hold the vol-down button and the power button continuously until at least one second after the Google logo flashes - this should put the device into fastboot mode if the bootloader is intact.
Something to remember is that Li-Ion batteries have a safety feature that prevents them from charging if the battery voltage gets too low. This is part of the reason why they are shipped with a 50% charge - they can sit that way for months and months only self-discharging at a very very slow rate.
OTOH, if you discharge the battery deeply and then let it sit for a long time afterward - especially if there is something like APX mode draining current - the battery voltage can fall below this "safety threshold voltage" and (even though it is still a "good battery" it can no longer be charged).
I'm not sure it the N7 can be started up while plugged in to only the charger; if it can, disconnecting the battery and trying to power up the device might be a way to discriminate "dead device" from "unchargeable battery".
good luck
Click to expand...
Click to collapse
I've tried this before. I still get a google screen, even after fully charging it. Does this mean that the battery has become unusable? How can I fix this?
Then try it again. It takes less time than typing a post into XDA.
There are two ways to try it.
1) Hold both Power & Vol-Down simultaneously, and keep holding them down until at least 4 seconds after the B&W "Google" text appears on the screen
2) Hold only the Power button down continuously, but be ready! Press the Vol-Down button as soon as the Google logo appears! - you only get less than a second to do this. (If you are late, the bootloader tries to boot the boot partition). Also, you need to keep holding the Power button down (3 or 4 seconds) after this - wait long enough that you are convinced that the fastboot screen is not going to occur.
As for the battery, you can pop off the back case and use a voltmeter to CAREFULLY measure the open-circuit voltage. The normal 0%-to-100% voltage range is about 3.6v - 4.15v. Obviously if it won't take a charge then there is a battery issue. BE CAREFUL - avoid doing anything which could short the terminals even momentarily.
bftb0 said:
Then try it again. It takes less time than typing a post into XDA.
There are two ways to try it.
1) Hold both Power & Vol-Down simultaneously, and keep holding them down until at least 4 seconds after the B&W "Google" text appears on the screen
2) Hold only the Power button down continuously, but be ready! Press the Vol-Down button as soon as the Google logo appears! - you only get less than a second to do this. (If you are late, the bootloader tries to boot the boot partition). Also, you need to keep holding the Power button down (3 or 4 seconds) after this - wait long enough that you are convinced that the fastboot screen is not going to occur.
As for the battery, you can pop off the back case and use a voltmeter to CAREFULLY measure the open-circuit voltage. The normal 0%-to-100% voltage range is about 3.6v - 4.15v. Obviously if it won't take a charge then there is a battery issue. BE CAREFUL - avoid doing anything which could short the terminals even momentarily.
Click to expand...
Click to collapse
I've tried holding down the buttons in various configurations at least 50 times already. As for the battery, there is current flowing, so I don't think this is a battery issue. Also worth noting is that if the device completely dies and I plug it in again, the charging battery sign appears (an empty battery slowly filling with white bars). Sometimes the device will give a black screen with little white sparks flickering randomly on it.
Well there have been several posts on here with identical symptoms, where the affected owner later reported that their tablet mysteriously started operating normally.
Unfortunately nothing consistent seems to have emerged from those reports.
You could try disconnecting the battery for a few minutes and reconnecting it to see if that makes any difference.
But whatever you do, you're gonna eventually have to press some buttons & the procedure I suggested is diagnostic for the bootloader, even if the boot or /system partition are borked.
BTW In my experience that battery charging graphic shows the charge state of the battery - does yours show closer to empty or full?
bftb0 said:
Well there have been several posts on here with identical symptoms, where the affected owner later reported that their tablet mysteriously started operating normally.
Unfortunately nothing consistent seems to have emerged from those reports.
You could try disconnecting the battery for a few minutes and reconnecting it to see if that makes any difference.
But whatever you do, you're gonna eventually have to press some buttons & the procedure I suggested is diagnostic for the bootloader, even if the boot or /system partition are borked.
BTW In my experience that battery charging graphic shows the charge state of the battery - does yours show closer to empty or full?
Click to expand...
Click to collapse
Mine shows the battery going from empty to full, like an animation. Also, I'm considering sending in the device for repair but I know that since the bootloader is unlocked it probably wouldn't be free.
Also can you link me to any posts related to this? They might be useful in solving my problem.
Thanks
Were you able to get your computer to recognized your Nexus when you connected it? I had to jump through a bunch of hoops with my Win8 machine to get the driver installed, because it didn't pass Microsoft's signature check. Maybe you can use Wug's toolkit to try to fix it, or at least re-lock the bootloader before sending it in for repair?
codehunter2000 said:
Were you able to get your computer to recognized your Nexus when you connected it? I had to jump through a bunch of hoops with my Win8 machine to get the driver installed, because it didn't pass Microsoft's signature check. Maybe you can use Wug's toolkit to try to fix it, or at least re-lock the bootloader before sending it in for repair?
Click to expand...
Click to collapse
After spending a few hours, I was able to get an adb driver installed onto my computer, I also had to jump through a lot of hoops (I run win8 too). Running adb devices shows the nexus in recovery mode. However, I can't access the bootloader whatsoever. Typing fastboot reboot-bootloader just hangs, and I've tried several toolkits but they just hang. I'm not sure if I can do anything unless I can access bootloader. If you know anything I can do please tell.
patil215 said:
Mine shows the battery going from empty to full, like an animation. Also, I'm considering sending in the device for repair but I know that since the bootloader is unlocked it probably wouldn't be free.
Click to expand...
Click to collapse
By coincidence I was charging mine right now (82%), so I shut it down and looked at that battery animation. (I have the v4.18 bootloader & Dec '12 hardware) First the "lightning bolt" symbol shows up in the battery icon, and the a little later, it performs a "filling the battery up" animation. But here's the important part: when that animation runs on mine, it starts from nearly, but not quite full (mostly white, not all black)- about 82%.
Can't tell exactly from the way you described your situation, but this (again) sounds like your battery is either not charging, or the bq27541 charge controller is reporting the wrong battery state.
Unplug the battery and let it sit for a while before reconnecting. If you have a safe way to measure the battery voltage, do so. You'll know right away if the battery is charged and the charge controller chip is lying.
---------- Post added at 08:14 PM ---------- Previous post was at 07:37 PM ----------
patil215 said:
After spending a few hours, I was able to get an adb driver installed onto my computer, I also had to jump through a lot of hoops (I run win8 too). Running adb devices shows the nexus in recovery mode. However, I can't access the bootloader whatsoever. Typing fastboot reboot-bootloader just hangs, and I've tried several toolkits but they just hang. I'm not sure if I can do anything unless I can access bootloader. If you know anything I can do please tell.
Click to expand...
Click to collapse
That is completely bizzare. The only way that a recovery can be started is via the bootloader. If the bootloader doesn't run, nothing can run. (The recovery is a booted kernel just as with the regular OS). Moreover, you saw the battery screen light up - if a recovery was (still) running, you would think something would show on the screen (although I guess recent versions of TWRP does screen blanking now). Very weird.
bftb0 said:
By coincidence I was charging mine right now (82%), so I shut it down and looked at that battery animation. (I have the v4.18 bootloader & Dec '12 hardware) First the "lightning bolt" symbol shows up in the battery icon, and the a little later, it performs a "filling the battery up" animation. But here's the important part: when that animation runs on mine, it starts from nearly, but not quite full (mostly white, not all black)- about 82%.
Can't tell exactly from the way you described your situation, but this (again) sounds like your battery is either not charging, or the bq27451 charge controller is reporting the wrong battery state.
Unplug the battery and let it sit for a while before reconnecting. If you have a safe way to measure the battery voltage, do so. You'll know right away if the battery is charged and the charge controller chip is lying.
---------- Post added at 08:14 PM ---------- Previous post was at 07:37 PM ----------
That is completely bizzare. The only way that a recovery can be started is via the bootloader. If the bootloader doesn't run, nothing can run. (The recovery is a booted kernel just as with the regular OS). Moreover, you saw the battery screen light up - if a recovery was (still) running, you would think something would show on the screen (although I guess recent versions of TWRP does screen blanking now). Very weird.
Click to expand...
Click to collapse
Can I have the links that you mentioned about users having identical symptoms that "fixed themselves"?
I really don't want to send it in for repairs if it's going to cost me. I'm a student with not much money to spare . One of the reasons I bought the nexus 7 in the first place.
bftb0 said:
By coincidence I was charging mine right now (82%), so I shut it down and looked at that battery animation. (I have the v4.18 bootloader & Dec '12 hardware) First the "lightning bolt" symbol shows up in the battery icon, and the a little later, it performs a "filling the battery up" animation. But here's the important part: when that animation runs on mine, it starts from nearly, but not quite full (mostly white, not all black)- about 82%.
Can't tell exactly from the way you described your situation, but this (again) sounds like your battery is either not charging, or the bq27451 charge controller is reporting the wrong battery state.
Unplug the battery and let it sit for a while before reconnecting. If you have a safe way to measure the battery voltage, do so. You'll know right away if the battery is charged and the charge controller chip is lying.
---------- Post added at 08:14 PM ---------- Previous post was at 07:37 PM ----------
That is completely bizzare. The only way that a recovery can be started is via the bootloader. If the bootloader doesn't run, nothing can run. (The recovery is a booted kernel just as with the regular OS). Moreover, you saw the battery screen light up - if a recovery was (still) running, you would think something would show on the screen (although I guess recent versions of TWRP does screen blanking now). Very weird.
Click to expand...
Click to collapse
I also fully charged the nexus 7 overnight. The battery icon now showed no animation because the battery was full (it first showed a picture of the lighting bolt battery, then a picture of a full battery) so I believe that the battery is working correctly.
patil215 said:
Can I have the links that you mentioned about users having identical symptoms that "fixed themselves"?
I really don't want to send it in for repairs if it's going to cost me. I'm a student with not much money to spare . One of the reasons I bought the nexus 7 in the first place.
Click to expand...
Click to collapse
I didn't make a record of them - you will need to search. What sounded very familiar was when you had said
patil215 said:
...black screen with little white sparks flickering...
Click to expand...
Click to collapse
What I recall - probably imperfectly - was that most of those cases seemed to spontaneously resolve when the owner charged their battery. And since your story started out with "black screen and little white sparks flickering", and "low battery" it sounded quite similar.
The various folks who mentioned this said things like "white lines flashing", "like sparks", or "like snow on an old-fashioned TV screen". Don't know if that will help you search, but they are in this forum (Q&A).
I also don't know if their tablets were in one particular mode or another (judging from a PC connected to the tablet - a black screen on the tab doesn't tell you anything) - I don't think any of them reported this.
As I said previously, that Black and White Google logo is produced by the bootloader. I just started my tablet in APX mode right now, and while the "charging battery" icon shows up when using the APX cold-start sequence (Vol-Up+Power), that B&W Google (text) Logo does not show up on the screen - the tablet goes directly from battery charging to APX mode (detected by looking at the PC - device shows up under "Other devices -> APX" in the device manager; VID/PID pair USB\VID_0955&PID_7330&REV_0103
)
So, my point is that it sure seems like your bootloader is there and capable of at least starting up at least part way.
What if your Vol-Down button was not working and you had a borked "boot" partition? If you had that combination, the bootloader wouldn't go into fastboot mode, as it would never see the Vol-Down keypress... and if your boot partition was borked, then you would never get any boot accompanied by a black screen.
At this point I think you should try observing the behavior of the USB port from the PC while trying to start it up... and even though you've tried it before, see if you can get the fastboot screen to appear. Perhaps there is something funky going on with your Vol-down button.
good luck
bftb0 said:
I didn't make a record of them - you will need to search. What sounded very familiar was when you had said
What I recall - probably imperfectly - was that most of those cases seemed to spontaneously resolve when the owner charged their battery. And since your story started out with "black screen and little white sparks flickering", and "low battery" it sounded quite similar.
The various folks who mentioned this said things like "white lines flashing", "like sparks", or "like snow on an old-fashioned TV screen". Don't know if that will help you search, but they are in this forum (Q&A).
I also don't know if their tablets were in one particular mode or another (judging from a PC connected to the tablet - a black screen on the tab doesn't tell you anything) - I don't think any of them reported this.
As I said previously, that Black and White Google logo is produced by the bootloader. I just started my tablet in APX mode right now, and while the "charging battery" icon shows up when using the APX cold-start sequence (Vol-Up+Power), that B&W Google (text) Logo does not show up on the screen - the tablet goes directly from battery charging to APX mode (detected by looking at the PC - device shows up under "Other devices -> APX" in the device manager; VID/PID pair USB\VID_0955&PID_7330&REV_0103
)
So, my point is that it sure seems like your bootloader is there and capable of at least starting up at least part way.
What if your Vol-Down button was not working and you had a borked "boot" partition? If you had that combination, the bootloader wouldn't go into fastboot mode, as it would never see the Vol-Down keypress... and if your boot partition was borked, then you would never get any boot accompanied by a black screen.
At this point I think you should try observing the behavior of the USB port from the PC while trying to start it up... and even though you've tried it before, see if you can get the fastboot screen to appear. Perhaps there is something funky going on with your Vol-down button.
good luck
Click to expand...
Click to collapse
UPDATE!:
Not sure if this will help at all. But I ran adb -d reboot bootloader, and the device just turned off. Completely. I turned it on again by holding power for 15 seconds but I got the exact same thing as before (google with black screen following). Once the device was on and I connected it to Windows, windows said "Windows detected malfunctioning device". But I couldn't duplicate the results again. Running adb -d reboot bootloader just hangs.
patil215 said:
UPDATE!:
Not sure if this will help at all. But I ran adb -d reboot bootloader, and the device just turned off. Completely. I turned it on again by holding power for 15 seconds but I got the exact same thing as before (google with black screen following). Once the device was on and I connected it to Windows, windows said "Windows detected malfunctioning device". But I couldn't duplicate the results again. Running adb -d reboot bootloader just hangs.
Click to expand...
Click to collapse
Incredibly, extra-ordinarily bizzare. ADB on the tablet side is a daemon process that runs in userspace. You would need a completely functional kernel to be running on the tablet, and a functioning ramdisk too in order to communicate with the tablet. ADB does not talk to fastboot mode, nor any other mode of the bootloader.
IF YOU ARE REALLY SHUTTING YOUR DEVICE OFF AND THEN SOMETIME LATER YOU ARE ABLE TO TALK TO THE TABLET BY USING THE adb COMMAND (not fastboot), THAT MEANS THAT THE BOOTLOADER IS SUCCESSFULLY BOOTING SOME (unknown) LINUX KERNEL.
That truly beggars the question of why you are seeing anything on the screen after the google logo. Did the previous ROM not have a splash-screen?
Well, if you can communicate with ADB it might be appropriate to try:
adb reboot recovery
and see what this does.
If you can find the device in the Windows device manager, what would be really, really helpful would be the device VID/PID pair.
The way you do this is like this:
1) Identify the device in device manager; right-click on it and select "Properties"
2) Select the "Details" tab
3) In the "Property" Combo-box pulldown, select the Property Name"
Hardware Ids
If you can get those values we can identify exactly which mode the device is in. There is a decoder ring at the end of the first post in this thread
OK, I'm starting to get fatigued, as I offer up both things to attempt as well as avenues of exploration, and you seem to simply ignore all of it.
I know you have tried it several times, maybe even a million times. Please try both methods of starting the tablet to try and intercept the initial phase of the bootloader startup and see if you can get the tablet to go into fastboot mode.
It's OK to try it and fail. But in all this back-and-forth, not once have you said, "yes I tried it again and it still failed". Try it and report the result, even if it fails.
Please try it again - both methods. In the second method where you click the Vol-Down button only after you see the B&W "Google" text, you need to do it really quickly - and not let your finger off the Power button either for several seconds.
---------- Post added at 06:08 PM ---------- Previous post was at 06:02 PM ----------
PS
The "-d" option to the adb command should only be needed if you were running an emulator via the Google SDK on the same PC.
If that were the case, when you ran the command
Code:
adb devices[/url]
you would see multiple lines of output indicating multiple devices on the machine - one for each running emulator, and one for the actual hardware device (so long as it is actually booted into a recovery or OS and you have the right drivers installed).
bftb0 said:
Incredibly, extra-ordinarily bizzare. ADB on the tablet side is a daemon process that runs in userspace. You would need a completely functional kernel to be running on the tablet, and a functioning ramdisk too in order to communicate with the tablet. ADB does not talk to fastboot mode, nor any other mode of the bootloader.
IF YOU ARE REALLY SHUTTING YOUR DEVICE OFF AND THEN SOMETIME LATER YOU ARE ABLE TO TALK TO THE TABLET BY USING THE adb COMMAND (not fastboot), THAT MEANS THAT THE BOOTLOADER IS SUCCESSFULLY BOOTING SOME (unknown) LINUX KERNEL.
That truly beggars the question of why you are seeing anything on the screen after the google logo. Did the previous ROM not have a splash-screen?
Well, if you can communicate with ADB it might be appropriate to try:
adb reboot recovery
and see what this does.
If you can find the device in the Windows device manager, what would be really, really helpful would be the device VID/PID pair.
The way you do this is like this:
1) Identify the device in device manager; right-click on it and select "Properties"
2) Select the "Details" tab
3) In the "Property" Combo-box pulldown, select the Property Name"
Hardware Ids
If you can get those values we can identify exactly which mode the device is in. There is a decoder ring at the end of the first post in this thread
OK, I'm starting to get fatigued, as I offer up both things to attempt as well as avenues of exploration, and you seem to simply ignore all of it.
I know you have tried it several times, maybe even a million times. Please try both methods of starting the tablet to try and intercept the initial phase of the bootloader startup and see if you can get the tablet to go into fastboot mode.
It's OK to try it and fail. But in all this back-and-forth, not once have you said, "yes I tried it again and it still failed". Try it and report the result, even if it fails.
Please try it again - both methods. In the second method where you click the Vol-Down button only after you see the B&W "Google" text, you need to do it really quickly - and not let your finger off the Power button either for several seconds.
---------- Post added at 06:08 PM ---------- Previous post was at 06:02 PM ----------
PS
The "-d" option to the adb command should only be needed if you were running an emulator via the Google SDK on the same PC.
If that were the case, when you ran the command
Code:
adb devices[/url]
you would see multiple lines of output indicating multiple devices on the machine - one for each running emulator, and one for the actual hardware device (so long as it is actually booted into a recovery or OS and you have the right drivers installed).[/QUOTE]
Sorry for not indicating the results of all of your suggestions.
Believe me, I have probably tried both of your button combinations at least two dozen times already. And I have gone down every avenue of exploration that you've suggested.
I've even tried every single one of the button combinations in the thread of nexus 7 button combinations. When I do anything from when the device is on, after 5 seconds or so the device turns off. Then the tablet shows the Google screen for about 5 seconds, no matter what I do. After the google screen comes a blank black screen (I can tell the device is still on because it's illuminated black, different from if the device was dead or powered off). There's not even a way I can get the tablet to power off - it just automatically restarts even if it's not connected to power, so I have to let it die or do a battery pull if I want to fix it. The black screen remains there indefinitely (until the battery runs out of course).
I've tried disconnecting the battery, leaving it disconnected for 30 minutes, connecting the device to power with the battery disconnected, having the buttons held down and connecting the tablet to wall power and USB pc, and different chargers. Nothing gives me a different result. The battery is alive and working, and the voltimeter did give me a current, sorry for not posting that earlier. About the random sparks/snow, there is really no pattern to when these appear, although they might be more frequent (but it might just be me) after a battery pull or full battery discharge.
Remember, I used to be able to access the bootloader but that stopped working for some reason. I'm kicking myself right now for not restoring the tablet when I was able to access bootloader, but I was busy at the time.
I've had some experience with rooting, locking, and unlocking other android devices, but this is something extremely weird.
Also, I should have posted the hardware ID's of the device before. I had done the exact same thing as you suggested when I was trying to install an adb driver for the nexus 7 (had to jump through a lot of hoops to get it working on win8, goddamn win8). The hardware ID's are USB\VID_18D1&PID_D001&REV_9999 and USB\Vid_18D1&PID_D001. According to the guide this means the device is in custom recovery, which makes sense because I was running Cyanogenmod 10 with clockworkmod recovery. If normally booting into the OS, the tablet should be giving me the default animated Cyanogenmod splash screen. Perhaps this issue is a bug with clockworkmod recovery?
I know that -d is to target a specific device, however I pulled up adb and went through each command methodically (really tedious) to see which ones would work. For some reason adb -d reboot-bootloader was the only thing that gave me a response, and even that won't do anything anymore (it just hangs, same with any other adb command). adb reboot recovery hangs also, and any fastboot command gives me waiting for device. Since I've installed a driver for it, in device manager the device shows up as Android phone and Android Composite ADB Interface. Windows tells me it's working properly (really? I'm not so sure windows).
I'd like to apologize for not indicating the results of trying your suggestions. Believe me, I have been trying them! I've spent probably a total of 12 hours trying to get this damn tablet fixed.
I'd also like to thank you. Without people like you this forum would not be any good. I am really grateful for any advice even if it does not work.
I know this is a hell of a problem. No goddamn clue how this happened. I love android but I sincerely hope that this is a clockworkmod recovery problem because otherwise that would make it a mistake on Google's (and therefore android's part). I know that the battery issues are quite frequent on android 4.2.2, but I have yet to find another user with my symptoms.
Lastly, do you know of some way to lock the device or destroy evidence of having the bootloader unlocked without being able to access the bootloader, in case this can't be fixed and I have to send it in for repair?
Click to expand...
Click to collapse
patil215,
Whew. That took you some time to write - thanks for all the details.
The USB\VID_18D1&PID_D001 USB Device Id sure does look like the custom recovery. I will assume - unless you say differently - that you would see this VID/PID pair any time you had the "black screen but with the backlight on".
Android uses this thing called the "BCB" (Boot Communications Block) to write instructions for the bootloader about what it should do when it starts up the next time. In the absence of seeing this, no doubt the bootloader has a default behavior. But basically, the way this works is that a "reboot" command eventually causes the kernel to write into this non-volatile memory area, and then a soft hardware reset occurs. The bootloader is aware of the BCB, and under normal circumstances, it will read it and attempt to follow the indicated boot mode - and then either erase the BCB or fill it with the "default booting instructions" just prior to booting a kernel or special-purpose mode previously indicated. In this way it will return to it's default behavior the next time it is booted.
The reason I mention it is that I have seen on other devices that got borked (HTC Droid Eris) in a way that sometimes those phones would always jump into a particular booting mode - and ignore any hard-button presses that would normally cause the bootloader to follow a different path. The Eris had/has "bootloader", "fastboot", and "OEM" modes and sometimes borked devices would not boot into anything other than the OEM mode.
So, since you apparently are seeing some evidence that a partially-functioning recovery is running, that sounds like a very similar scenario - the Asus bootloader is always booting to your (damaged?) recovery.
So, that's materially different (I think) than what other folks might have experienced it. The first time I've seen it here, although TBH I've only been looking in here for a little less than 3 months.
I don't know what else to suggest - it sounds like maybe you've tried things like "adb shell" commands?
If the bootloader can't be forced into fastboot mode, that (possibly damaged) recovery mode is the only privileged thing you have left. It seems to me that if you can't get into that somehow - adb being the most obvious route - then there is little left to do.
No, I don't know how to relock the bootloader without using the bootloader. That's probably something that can only be done with factory methods (possibly in APX mode).
Sorry.
Hey everyone I really hope you can help me out here. Last night my completely stock Nexus 7 2012 locked up during normal use. It had KitKat 4.4.4 on it not rooted or unlocked. I THINK usb debug was enabled but don't honestly remember. After the lock up I forced it to power off. When it started up again, it was stuck with the 4 circles going round and round. After a long wait I went into recovery and tried to wipe the cache. This went on for almost 10 min but never completed. I forced it to power off again (and here is where I panic and things get fuzzy. I tried to get back into recovery and just restore it but I can not get it to do anything except boot to the dead android picture and a message that says NO COMMAND. I've tried to use the VOL UP and Power button sequence to get the menu and it won't come up. It stays on that screen for a few seconds and then it acts like its restarts but I never see the google logo just this dead android flashing on and off with the no command error. I've read several threads, tried the WUG toolkit as well as skipsoft toolkit but with the device stuck in this loop nothing can communicate with it. I removed the cover and unplugged the battery which gets the machine to shut down but when it powers back on even with key sequences I can't get anything but this dead android. I can use power and VOL up to get into APX mode but that is my only other option. Please give me some more suggestions!
Well things have gotten worse now I can no longer get past the black and white google screen. I'm guess this thing is just toast.
How old is it? If it's under a year, you can RMA it back to ASUS and they'll fix it for free. Since you haven't rooted it nor unlocked it (although I don't think that would be an issue anyway), they shouldn't have any issue with repairing it. Just be sure you didn't leave any signs that you opened it or else, that will void the warranty and they won't repair it for free.
Its exactly 2 years old today. It was a birthday present. funny how it chose today to die.
Okay just so I can have some closure here,
The tablet will not shut off when I hold power button it shuts off and comes right back on to the google logo.
I can NOT get into boot loader or recovery at all. No key sequences work what so ever. I've been into recover and boot loader before on this device so its not that don't know how.
The only time it gets detected by my PC when plugged in via usb is if its int APX mode which as far as I can read is useless to me.
So is there any other secret or is it just trash now?
Thank you.
My wife's was doing this when it failed an OTA. Hold the power button long enough the screen will go dark for a couple seconds.when it's dark, hold all three buttons down and wait.it will go into fastboot.use nexus root toolkit to flash stock+ unroot and select bootloop .
---------- Post added at 09:56 PM ---------- Previous post was at 09:55 PM ----------
Ps it did this because she accepted an OTA not knowing I had TWRP on there.
KANDL said:
Okay just so I can have some closure here,
The tablet will not shut off when I hold power button it shuts off and comes right back on to the google logo.
I can NOT get into boot loader or recovery at all. No key sequences work what so ever. I've been into recover and boot loader before on this device so its not that don't know how.
The only time it gets detected by my PC when plugged in via usb is if its int APX mode which as far as I can read is useless to me.
So is there any other secret or is it just trash now?
Thank you.
Click to expand...
Click to collapse
"The tablet will not shut off..." <<---- This suggests that you are seeing or observing something happening. But based on your previous posts I can not tell exactly what you are now observing - the black & white Google logo?
I would start first with trying to determine if the battery is capable of being charged. The last thing you want to be doing is fooling around with this stuff with a nearly dead battery.
If you put it on a 2A wall charger (*not* a PC USB port), does the tablet warm up a little after 20-30 minutes? If so, leave it on the charger for at least 2 hours. (Heck, even if it doesn't warm up, same advice - put it on the wall charger for at least 2 hours)
OK, next item for you to consider. In Android devices, there is usually a nonvolatile storage area (maybe in the "misc" partition?) called the BCB (Boot Communication Block). The bootloader will always look at that area first, and if there are no boot instructions in there, by default the bootloader will attempt to load & jump to the entry point of the contents of the LNX partition (Linux boot partition). This would cause a "normal" Android boot to occur by default when turning the power on. The other two common instructions in the BCB are for a reboot into the recovery, or instructions for the bootloader to stay resident but drop into it's fastboot mode.
Why am I telling you this? Because there are certain pathological situations that can develop into loops without apparent escapes. Imagine that the tablet was sitting in custom recovery mode, and the dummy behind the PC keyboard flashes some random garbage to the recovery partition, and then uses the touch interface to reboot into recovery. What happens is that "boot to recovery" instructions are placed in the BCB, and a soft-reset of the device occurs... which (when the hardware finishes resetting) loads up the bootloader.**
Now the bootloader sees the "boot to recovery" instruction in the BCB, and attempts to load the garbage in the recovery partition. Eventually - either due to a watchdog timer reset, or a illegal instruction trap, the device will soft-reset again... WITHOUT EVER CLEARING THE CONTENTS OF THE BCB.
In this example, the bootloader is intact and operational, but the looping behavior continues until the battery drains. You don't get an opportunity to communicate with it in fastboot mode because it is always trying to load the bad recovery. Either there is a way to break out of this death spiral... or their isn't.
Now, one more thing - I lied slightly right around the ** annotation.
On the Tegra3 SOC, there is a kind of micro-kernel inside the Tegra3 that is responsible for loading the bootloader. Simpler processors of old would simply load a memory page at a specific hardware memory address when they reset, but this is far more sophisticated: the little micro-kernel in the Tegra3 can evaluate the bootloader to see if it has the correct cryptographic signature and so forth.
If that micro-kernel doesn't like what it finds, the Tegra3 will put the USB port into APX mode. This is important because it is diagnostic: if your tablet always goes into APX mode, for instance after disconnecting/reconnecting the (charged) battery and then powering up the device, then you are probably out of luck; but if it doesn't go into APX mode, that suggests that the bootloader is actually healthy, but perhaps thrashing in one of those nasty boot-loop cycles.
OK, still with me?
Have you looked at this thread carefully?
http://forum.xda-developers.com/showthread.php?t=2133986
It suggests that possibly you can get the bootloader to ignore the contents of the BCB by a carefully-timed press of the Vol-Down button - which, if it works - should let you escape to fastboot mode. This is documented in the above thread as "bootloader interrupt".
So, questions for you:
1) Are you sure the battery is well charged? (Not easy to tell without a voltmeter or heating of the tablet during charging - the temperature of the tablet will drop after it finishes charging. One way to be sure of things is to disconnect the battery, reconnect it, and then put it on the wall charger. That way you can be sure that the tablet is not on, so any heat would be due to battery charging, not other components running. FWIW, a discharged battery will be about 3.5v, and charged about 4.15v.)
2) Does the tablet always go into APX mode when it starts up, even if you only press the power button?
3) Once the battery is charged, what are you seeing on the screen during start-up? After you have disconnected the battery and reconnected it, do you see anything on screen when you put the tablet on the charger?
bftb0, Thank you for attempting to help me out, I really appreciate it. I understand 99% of what you wrote, and that gives me a little bit of hope! Let me begin by answering your questions.
1. I am certain the battery WAS charged. as I had just pulled it off the charger when this happened. Also I'm certain the battery IS charging when I plug it in. It does get warm after a while. The battery did drain down now since my last post, but I have removed the cover and unplugged the battery to get it to power off. Now it is currently charging back up as I'm typing this. I can see the battery charge indicator on the screen while its laying here.
2 and 3. The tablet does NOT go into APX mode by its self. It only does that when I hold power and VOL+. It now currently powers on with a press of the power button goes to the black screen with with the white google logo and stops. After that I can no longer get it to power off without manually disconnecting the battery. I can get it to reboot and go right back to the same google logo. Prior to it doing that it would go to the android on its back and just say no command. That screen would flash on and off like it was contentiously rebooting. However after trying all day to get some sort of menu to come up and different key sequences it now only goes to the google logo and stops.
I have it currently charging and will let it charge to full capacity while waiting for you to reply. I tried and tried to get the boot interrupt to work from the thread you posted in your reply and it wither does not work or I'm simply not doing it right but I'm willing to try some more if it will save this thing and I don't have to go buy a new one.
Thank you again for your help!
Well, because you have a pure stock tablet and the problem occurred spontaneously and under innocuous operating conditions, the most likely explanation is some type of hardware failure affecting the eMMC NAND chip.
Even if that is the case ... AND you successfully are able to get to fastboot mode ... it still might not be repairable. It could be a modest failure (e.g. something affecting the cache partition only, which could knock offline both the normal boot as well as the recovery boot), or it could be an enormous fraction of NAND.
eMMC NAND is supposed to be able to degrade gracefully, so there is a small chance that erasure and formatting of partitions will release blocks that have failed. But it could also be that the failure is extremely severe and no recovery is possible even if the bootloader is still intact.
I imagine you've already tried it, but since it will be your only possible means of rescue I would try the bootloader interrupt trick (Vol-Down approximately when the b&w Google logo appears - hold it down for 3-4 seconds)
Since the tablet gets stuck in a hardware reset loop, you should probably unplug the battery after every failed attempt, start it up normally (power button only), and then press and hold Vol-Down as soon as you see the Google b&w logo. Perhaps with the use of a stopwatch, you could experiment with slightly different timings, possibly even try the button press a second or two before you expect the logo to appear. I am not aware of any other way to get to fastboot (without having a booted kernel as in the recovery or normal os); and it may also be that the only time that the Vol-Down button has any effect is under the "default" (empty) BBC contents. If that is the case you are probably SOL.
The objective is to try and get the tablet into fastboot mode by any means possible.
If it were happening to me, and I was able to get that to happen, the next thing I would do would be to erase the entire tablet (except the bootloader) using fastboot, and then follow that up with an installation of a stock recovery (and formatting of cache, system, and userdata in that order), and then follow that up with a "factory reset" using the stock recovery.
If you can get just the recovery and (bootloader) fastboot mode working again, there is an outside chance that the tablet could be put back into service.
A little bit of explanation is in order here for me to explain why I am suggesting this. Sometime after I got my tablet, I spent a bunch of time dumping *all* the device partitions (things like MISC, USP, PERS, etc in addition to the "normal" Android partitions) before/after certain fastboot operations. What I noticed - by accident - was that I was seeing data that belonged in a certain partition showing up in other partitions. And always in block-sized offsets.
I think that what I was observing was an artifact of the eMMC wear leveling / block remapping that is part of the device's FTL (Flash Transition Layer). Literally, blocks were being shuffled around - even across partition boundaries - when they were in an unused/erased state.
In addition, if you look at the Google instructions for flashing a factory image, you will note that sequence is
erase p1
erase p2
...
erase pN
(followed by)
format p1
flash p2
format p3
...
That is, **as much as possible is erased before anything is put back into service**
It is my presumption that this happens to give the wear leveling and bad block remapping process of the eMMC chip maximum flexibility (as most everything in the device is marked as not in service it should be easy to remap based on block write counts as individual partitions are put back in service via via flash and format operations). Can't prove that though.
It looks like you did your reading about APX mode - there is a risky and fairly complicated procedure available to rooters that allows them to capture some custom (unique per tablet) file blobs that allow re-installation of a bootloader from APX mode, but is a procedure that has to be performed ahead of time. (And because the file blobs are unique per tablet - encrypted & signed with a unique hardware identifier, you can't get someone else to generate them for you) So APX mode is of no value to you afaik. It's barely of value to rooters as well. (I will say that I haven't kept up over the last year, so there is always the chance that someone discovered something new wrt the Tegra3 and APX mode that I don't know about - but that's the way it was a year ago or so)
Well, good luck with your tablet - I suspect you are going to need a bit of good fortune.
Thanks you so much for your help. I will continue to try the boot interrupt and see if I can get it to go. Failing that I guess I'll be shopping for a new one. I really appreciate your time in trying to help me.
Hi everybody,
What Happened:
My phone has suddenly become totally unresponsive. I have been using it most of the day, it was sitting at around 70% the time that it happened, but it is now a totally black screen. I had just taken it out of my pocket and it was suddenly like this.
The only idea I could come up with as to why this happened is that I charged it off of a JBL Charge 2 last night. I'm not sure if that may have messed with the battery, but I do find it odd that it's totally unresponsive while plugged in.
I was running android 7.1.1 DP2, with the ElementalX kernel 4.0 I believe. I was also rooted with SuperSU. What's really odd is that I hadn't done anything new recently besides install uTorrent and VLC media player. Otherwise, my routine has not changed one bit. Up to when the phone actually died, I hadn't even used either of these new apps the entire day.
What I've Tried:
I have tried plugging it in via AC, via USB, I've tried booting into recovery or fastboot, but there is zero response from the phone. No indicators on the screen, no LED blinks, no vibrations, nothing.
What I'll Try:
If anyone has any experience with this happening, I could use some advice. Otherwise I'm just going to wait it out, consider an RMA I guess. However, my device did have the bootloader unlocked and was rooted, so.... I hope it comes back by itself.
My advice is to keep it plugged in, or see if there is a response on the computer perhaps on fastboot, upon using the bootloader keys. I haven't had this, just a few suggestions. Good luck!
PS: A RMA will probably be needed, there are much more experienced people around here. Sure you may get replies later.
Good luck?problem all nexus 6p!!! Lg responds repay helps, hawuei what to do? problem arises with nogaut not be our fault, how to fix this? My phone now in service but to be fair this? warranty and having to wait ..
I am unable to boot up the device. I tried all (power + Vol Up) key combos, not working. Is there anyway to pull data out from the device?
easyxpress said:
I am unable to boot up the device. I tried all (power + Vol Up) key combos, not working. Is there anyway to pull data out from the device?
Click to expand...
Click to collapse
No fastboot or custom recovery ?
Then no theirs nothing really to do
Maybe a battery replacement would boot it up
Sent from my ONEPLUS A6010 using Tapatalk
No fastboot or custom recovery. I'm wondering if the *storage* can be pulled out like a hard drive?
easyxpress said:
No fastboot or custom recovery. I'm wondering if the *storage* can be pulled out like a hard drive?
Click to expand...
Click to collapse
Nope it's just a chip on a circuit board
Sent from my ONEPLUS A6010 using Tapatalk
easyxpress said:
I am unable to boot up the device. I tried all (power + Vol Up) key combos, not working. Is there anyway to pull data out from the device?
Click to expand...
Click to collapse
Not enough information. What did you do prior to your phone failing to boot? Was there a software mod you installed? What were the symptoms the phone showed the last time it was on? Any problems before it failed to boot like an old battery, misbehaving ROM, poor charging?
Basically, you need to identify (help us identify) the cause of your phone not booting. We cannot find the solution to a problem we don't know the cause of. The problem must first be defined and then we work from there.
All the best.
twistyplain said:
Not enough information. What did you do prior to your phone failing to boot? Was there a software mod you installed? What were the symptoms the phone showed the last time it was on? Any problems before it failed to boot like an old battery, misbehaving ROM, poor charging?
Basically, you need to identify (help us identify) the cause of your phone not booting. We cannot find the solution to a problem we don't know the cause of. The problem must first be defined and then we work from there.
All the best.
Click to expand...
Click to collapse
Prior to the phone failing to boot, the phone kept crashing. I saw the screen turning into *mess* and then the phone shut off by itself. Initially, I was able to boot up the phone after the crash, however the screen would get mess up and shut off again after a few minutes. Eventually, It got harder and harder to turn on the phone until it finally failed to boot (die). At this point, the phone seems dead. When I plug in the charger, there is no response of any kind, just black screen.
At one time, when the phone was on its last legs, I was able to boot into the Recovery mode, the phone seems to stay in that mode without the crash. Unfortunately, I didn't stay long enough in the Recovery mode to confirm this.
The phone was running on Lineage of Android 8. I have been using the phone for two years, the battery is surely weakened but can still last an hour or two for continual Youtube watching. I didn't do any software update after the Lineage Android 8's last nightly build.
Hope you can help and give some pointers. Thanks.
-- Joseph
easyxpress said:
Prior to the phone failing to boot, the phone kept crashing. I saw the screen turning into *mess* and then the phone shut off by itself. Initially, I was able to boot up the phone after the crash, however the screen would get mess up and shut off again after a few minutes. Eventually, It got harder and harder to turn on the phone until it finally failed to boot (die). At this point, the phone seems dead. When I plug in the charger, there is no response of any kind, just black screen.
At one time, when the phone was on its last legs, I was able to boot into the Recovery mode, the phone seems to stay in that mode without the crash. Unfortunately, I didn't stay long enough in the Recovery mode to confirm this.
The phone was running on Lineage of Android 8. I have been using the phone for two years, the battery is surely weakened but can still last an hour or two for continual Youtube watching. I didn't do any software update after the Lineage Android 8's last nightly build.
Hope you can help and give some pointers. Thanks.
-- Joseph
Click to expand...
Click to collapse
This appears to be hardware failure. The SoC is most probably dead. You should have recovered your data when it was still able to boot. Right now I think it's too late.
twistyplain said:
This appears to be hardware failure. The SoC is most probably dead. You should have recovered your data when it was still able to boot. Right now I think it's too late.
Click to expand...
Click to collapse
I just plugged in the phone. Miraculously, after few minutes, it did come up with the boot screen (with some messy lines), see the attached picture. However, It didn't go beyond the boot screen and recycle again for 2 or 3 times and then no more. I was able to duplicate this recycling situation several times after plugging it to the charger. Also, I was able to push it into the Recovery mode, but it only stay at the boot screen (with lines) and shut off again after few seconds.
What do the messy lines on the boot screen suggest? Is it the battery totally dead? Or, is the charging system faulty that somehow it doesn't have any enough juice to push thru beyond the boot screen and hence shut off?
-- Joseph
easyxpress said:
I just plugged in the phone. Miraculously, after few minutes, it did come up with the boot screen (with some messy lines), see the attached picture. However, It didn't go beyond the boot screen and recycle again for 2 or 3 times and then no more. I was able to duplicate this recycling situation several times after plugging it to the charger. Also, I was able to push it into the Recovery mode, but it only stay at the boot screen (with lines) and shut off again after few seconds.
What do the messy lines on the boot screen suggest? Is it the battery totally dead? Or, is the charging system faulty that somehow it doesn't have any enough juice to push thru beyond the boot screen and hence shut off?
-- Joseph
Click to expand...
Click to collapse
what happened to TWRP ? thats stock recovery
will it enter fastboot mode ? if you can get into TWRP their is a chance of off loading your userdata to a PC
easyxpress said:
I just plugged in the phone. Miraculously, after few minutes, it did come up with the boot screen (with some messy lines), see the attached picture. However, It didn't go beyond the boot screen and recycle again for 2 or 3 times and then no more. I was able to duplicate this recycling situation several times after plugging it to the charger. Also, I was able to push it into the Recovery mode, but it only stay at the boot screen (with lines) and shut off again after few seconds.
What do the messy lines on the boot screen suggest? Is it the battery totally dead? Or, is the charging system faulty that somehow it doesn't have any enough juice to push thru beyond the boot screen and hence shut off?
-- Joseph
Click to expand...
Click to collapse
Yup...This phone is dead. I have seen a similar le pro 3 posted here on XDA with the same streaks along the display. It's definitely a hard brick. No way to get around it that I know of. I'd like to rope @tsongming in on this. He has seen a few dead pro 3's so this is within his expertise.
Sent from my LeMobile Le X526 using XDA Labs
twistyplain said:
Yup...This phone is dead. I have seen a similar le pro 3 posted here on XDA with the same streaks along the display. It's definitely a hard brick. No way to get around it that I know of. I'd like to rope @tsongming in on this. He has seen a few dead pro 3's so this is within his expertise.
Click to expand...
Click to collapse
Sorry bad news.
As twistyplain said, your phone is absolutely fried, and there is no solution.
It's definitely no brick, that is a hardware issue... Most likely shorted solder connections. The same thing happened to two of our X727s, we have one left that still works.
I highly recommend buying a seemingly unbrickable Xiaomi phone. Their budget models are awesome and of course their flagships are awesome. Everyone in my family has Migrated to Xiaomi . I currently have Android 10 working flawlessly.
Thanks for the info. I made a mistake of not backing up the photos from the phone. I'm still hoping for a slim chance and searching that some of the repair shops (in China?) are somehow able to boot up the phone and retrieve the photos for me. Meanwhile, I'll check into Xiaomi.
-- Joseph
easyxpress said:
Thanks for the info. I made a mistake of not backing up the photos from the phone. I'm still hoping for a slim chance and searching that some of the repair shops (in China?) are somehow able to boot up the phone and retrieve the photos for me. Meanwhile, I'll check into Xiaomi.
-- Joseph
Click to expand...
Click to collapse
If you are in China and located in a large city or tech industrial area you should have plenty of shops that repair at the component level.
Your phone could very likely be repaired by a shop that has a hot air rework soldering station with an electron microscope.
We used to have these types of places in the US but they have all gone out business, replaced by board swappers, who charge a lot. I would suspect that you could get it repaired in China for 100 yuan or less.
I worked in Beijing for 3 months, about 18 years ago and these types of places were everywhere.
Greetings everyone,
As the title of the thread states, I have in my possession a M1A1 that is stuck on a Bootloop.
First of all, let me explain the situation a bit. This phone was accidentally put inside a washing machine, lasting inside there for what may have been a good 20 minutes until it was noticed there and promptly removed.
Upon removal it was still showing some signs of life, such as the LED lights going off. My first decision was to quickly open the phone and remove the battery in order to avoid further possible damage. I then decided to disassemble the phone while at the same time removing the water and letting the components dry up in a lit location. Once they dried up, I proceeded to wash them with alcohol, fully bathing the motherboard while giving a slight rinse to the other components, and used a soft brush to very gently clean the slight corrosion that formed in some places. I repeated this process up to 4 times, each time letting the components dry before giving it another go. It is worth mentioning that i was not able to remove the electromagnetic shielding due to the lack of tools.
Upon seeing no more corrosion, I decided to reassemble the phone and test if it was still alive. To my surprise, it did actually turn on. However, once it got to loading the OS, the loading bar got frozen and the phone restarted, resulting in a bootloop. I argued that maybe, somehow, the OS may have been corrupted, and I decided to try to flash a new ROM. I don't exactly remember whether I first tried via Fastboot or if I went straight to unlocking the phone in order to use TWRP, but long story short, I ended up unlocking the phone and therefore wiping all the data, however allowing me to freely use TWRP to flash new ROMs.
In retrospective, that may have been an extremely foolish decision, as no matter which ROM I tried, the result was the same as it previously was: The phone shows the Mi logo, it then starts loading the OS, the loading animation freezes up, and then restarts. So not only did I end up wiping all the data, but I am still stuck with the same problem.
This is my main issue. I do not know how to identify what is causing this Bootloop. The phone is at least somewhat working, seeing as how I am able to fully use TWRP. Is there maybe some component that may have been fried that is preventing the booting sequence? I would really appreciate some pointers. Thanks.
Something similar happened to me using the adriane tool , I resolved it by unpluging the phone from the PC and the forcing the phone off and rebooting into fastboot mode, and when I got it to boot the first boot was slow, A couple minutes maybe ?. I don't know if this can be helpful, I wish I could do more bro.
lionr2 said:
Something similar happened to me using the adriane tool , I resolved it by unpluging the phone from the PC and the forcing the phone off and rebooting into fastboot mode, and when I got it to boot the first boot was slow, A couple minutes maybe ?. I don't know if this can be helpful, I wish I could do more bro.
Click to expand...
Click to collapse
Hmmm, I don't think this approach would work for me. I have tried every possible rebooting combination to no result, but I really appreciate the help man.