Question about the bootloader - Nexus 7 Q&A, Help & Troubleshooting

I know that the Nexus 7 has a bootloader whose digital signature checks can be disabled. But can anyone tell me about the very beginning of the device's boot process? Is the first-stage bootloader signature checked by the boot ROM? Can it be replaced?

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[Q] L5 Check if bootloader is unlocked?

Hello, is there any way to check if my bootloader is unlocked? I want to install CWM but i don't know if i unlocked the bootloader correctly, after copying it and writing reboot in adb the phone just turned off. But it did start with no problems after i turned it on after that, and after that i copied the bootloader and it had a different MD5 than the backup i made. Also my firmware is 4.1.2 E61020g-EUR-XX, does it mean i have v20 baseband? I just want to be sure before i flash CM 10.2 because i don't want to brick my phone.
bump. No one knows how to check this? Or maybe is there a way to unbrick my phone if the bootloader is locked and i flash CWM? If there is a way to unbrick then i will just flash it and hope that there will be no brick.
flash cwm and boot into it, if it shows the cwm, the bootloader is unlocked
if it not unlocked, it will show an bootloader security error or something like that
But if it shows the error what will i do then? I don't want to lose my phone.

Help relocking RAZR M bootloader

First, let me say this because i've used xda for a while and i know im going to get these responses:
I know this wont reinstate my warranty...
Why? Because I want to. I understand you think it's useless but it's not your phone...
I have tried "fastboot oem lock" and it doesnt work...
I've searched Motorola's site, got on a chat with them which was useless, and searched xda...
So I booted into AP fastboot and connected to my computer. Opened CMD and typed "fastboot oem lock begin"
That seemed to start the process so then ran RSD lite (as admin) and flashed a signed xml of 4.1.2
Yes, I edited the XML first and removed the 2 lines with "getvar" in them
RSD finished and the phone rebooted (which was great because before it was hung up on the unlocked bootloader warning)
Unfortunately after turning the phone off and then back on, the unlocked bootloader warning screen still came up.
And after booting back into AP fastboot it still said UNLOCKED.
did i miss a step?
I need to relock the phone. if anyone has useful information it would be extremely helpful. in the event it just cant be done thats fine. but i feel like it can, because after fastboot oem lock begin the command prompted told me that now i can flashed the signed images.
well crap. i may have just answered my own question. do i have to flash manually through CMD (ie fastboot flash system system.img) AND THEN run fastboot oem lock at the bottom? i'll try it tomorrow.
before i started this the phone was stuck on the bootloader warning screen so if anyone is stuck at that point this will allow you to boot up your phone. and if my results are typical, it did not relock the bootloader (obviously). hope I helped someone. hope someone can help me. thanks.
most likely not feasible
unlocking razr m involves phisically blowing a q-fuse, so you can't go back to locked
even if you could, it would be traced forever that you've unlocked the BL
You can relock the boot loader on the Dev edition, but once unlocked you can never go back to original status 0 of the boot loader and the boot logo will always display the warning even if you relock the boot loader. You have to flash that partition with another logo image to avoid that.
You also need to wipe the user data partition in fastboot first for the fastboot oem lock begin command to complete successfully.
Once that is done, when it reboots you will see that in fastboot it will display status 2 locked instead of status 3 unlocked.
This is a physical change that happens to the hardware when you unlock the boot loader an efuse on the board is blown and that memory location is permanently programmed. Its not even a question of them knowing, even though they do of course, the device itself is altered.
From my goodies
http://forum.xda-developers.com/attachment.php?attachmentid=2201206&d=1376991889
Flash from cwm or twrp.
Trade a locked one for your unlocked one? Lol I'm stuck locked on the newest ota
Sent from my XT907 using Tapatalk

[Q] bootloader issues

So a while ago I rooted my phone but messed it up because I uninstalled a few too many system apps. I just dealt with it for a few months since I could still make calls (but not much else). I finally bit the bullet to look into flashing the stock rom again, but to do so it looked like I had to install a custom recovery, but to do that, unlock the bootloader. So I first unlocked the bootloader using motopocalypse (batch file didn't work but apk did), and got the expected BOOTLOADER UNLOCKED message at bootup, with fastboot saying unlocked, code 3. I then tried flashing CWM recovery via Rom Manager, and it seemed successful, but I was unable to boot to it either from the UI of ROM manager or from holding the buttons during bootup, it would just hang for a few more minutes than normal at the BOOTLOADER UNLOCKED screen, then boot up like normal. So I kept reading, found RSDlite, and was able to flash the stock rom, which I downloaded from the internet and the phone boots up fine, but now fastboot says locked, status code 2, and motopocalypse does not unlock it again (either the batch file or the apk), but I still get the BOOTLOADER UNLOCKED message at bootup. So I'm not sure if my bootloader is unlocked or not and if I can proceed with installing CWM recovery again, so i can make a full backup in case I mess something up again.
So how do I reunlock the bootloader, or verify if it's locked or not?
First, CWM and TWRP aren't official for this phone, so you can't use their apps to flash. You'll need to use fastboot, Flashify, or Rashr. Second, you're still unlocked, we've seen this error come from bad flashes. What is the complete text on your FB screen. You should be able to clear this by re-flashing with RSD. What firmware did you attempt to flash?
Sent from my HTC6525LVW using Tapatalk
RikRong said:
First, CWM and TWRP aren't official for this phone, so you can't use their apps to flash. You'll need to use fastboot, Flashify, or Rashr. Second, you're still unlocked, we've seen this error come from bad flashes. What is the complete text on your FB screen. You should be able to clear this by re-flashing with RSD. What firmware did you attempt to flash?
Sent from my HTC6525LVW using Tapatalk
Click to expand...
Click to collapse
FB screen:
Code:
AP Fastboot Flash Mode (S)
10.9B(*) (sha-61146a2, 2014-05-02 00:54:39)
eMMC Info: Size 8GB
Device is LOCKED. Status code: 2
Battery OK
Transfer Mode:
USB connected
Fastboot reason: Reboot to bootloader
usb connected
I've tried reflashing with RSD previously but no change. I could try it once more if you want.
Not entirely sure what you're asking for with the firmware version, but the image I used was for android 4.4.2, version 183.46.10.XT907Verizon.en.US.
modemman11 said:
Device is LOCKED. Status code: 2
Click to expand...
Click to collapse
I think your boot loader is still LOCKED. Mine is showing UNLOCKED. Status code: 3. You cannot flash a custom recovery on a phone with a locked BL. You need to motocalypse again!
To trace the issue from the ground up, if you're just trying to reinstall stock ROM, you should be relying on RSD instead of trying to mess with custom recoveries and BL unlocking. Just flash .10 (not .15) via RSD, root via Towelroot and you can start fresh.
Unlocking your BL is still highly recommended, though, 'cuz it's now or never.
Sent from Google Nexus 4 @ CM11
[WARNING: XDA Premium 4.0.13 lacks Signature function - do not update]
Code 3 as well.
Sent from my XT907 using XDA Free mobile app
rahimali said:
I think your boot loader is still LOCKED. Mine is showing UNLOCKED. Status code: 3. You cannot flash a custom recovery on a phone with a locked BL. You need to motocalypse again!
Click to expand...
Click to collapse
Yes, that's why I'm asking. So I've got one vote for unlocked, one for locked. As I said though, motopocalypse isn't working a 2nd time.
AndyYan said:
To trace the issue from the ground up, if you're just trying to reinstall stock ROM, you should be relying on RSD instead of trying to mess with custom recoveries and BL unlocking. Just flash .10 (not .15) via RSD, root via Towelroot and you can start fresh.
Unlocking your BL is still highly recommended, though, 'cuz it's now or never.
Click to expand...
Click to collapse
I would like to flash custom ROMs later down the road, but for now I just want to get the stock stuff going.
On a side note, the version of the image I downloaded was 183.x.x, but my mother, who has the same phone, purchased at the same time, and has never rooted it or anything, has version 182.something, and that is also the version I had before I started messing with the bootloader/recovery stuff. The two versions were released at the same time, but I don't know what determines which version you got if you just did OTA updates, or if it even matters. Speaking of OTA updates, the version I downloaded is prompting me to do an OTA update now to another 183.x.x version. I wonder if I'd be able to grab the 182.x.x ROM from my mom's phone without rooting it via fastboot or something.
The 182/183 does not matter regarding root/boot loader unlock its the .10/.15 that matters do not take the .15 without unlocking your boot loader....
We cannot teach people anything; we can only help them discover it within themselves.
So no other thoughts? What would happen if I flashed a custom rom/recovery with a locked bootloader? I tried flashing the ROM again and fb still says locked, code 2, and motopocalypse still doesn't do anything like it did the first time.
modemman11 said:
What would happen if I flashed a custom rom/recovery with a locked bootloader?
Click to expand...
Click to collapse
It won't let you flash a custom recovery. This is the difference between locked and unlocked.
modemman11 said:
So how do I reunlock the bootloader, or verify if it's locked or not?
Click to expand...
Click to collapse
If your bootloader is relocked for some reasons, try unlocking it again with
Code:
fastboot oem unlock
lem22 said:
It won't let you flash a custom recovery. This is the difference between locked and unlocked.
Click to expand...
Click to collapse
I guess what I'm asking is, will it let me flash it but then the phone won't work or will give an error on boot, or perhaps brick my phone? Or will it just not flash in the first place? Because if it's the latter, then I can just try to flash a custom ROM/recovery and if it works then I know it's unlocked.
If your bootloader is relocked for some reasons, try unlocking it again with
Code:
fastboot oem unlock
Click to expand...
Click to collapse
Code:
D:\adt-bundle-windows-x86-20140702\sdk\platform-tools>fastboot oem unlock
...
(bootloader) fastboot oem unlock [ unlock code ]
OKAY [ 0.031s]
finished. total time: 0.031s
Still locked code 2 though. Looks like it wants an unlock code from Motorola's website, I tried following the steps to get the code but it says I'm not eligible for bootloader unlock. So unless there's another way to get the unlock code...
modemman11 said:
I guess what I'm asking is, will it let me flash it but then the phone won't work or will give an error on boot, or perhaps brick my phone? Or will it just not flash in the first place? Because if it's the latter, then I can just try to flash a custom ROM/recovery and if it works then I know it's unlocked.
Click to expand...
Click to collapse
A "Code 0" locked device would refuse flashing an unofficial or older recovery. I have no idea about Code 2 though.
From what I was able to locate status code 2 indicates that the bootloader has been unlocked and relocked like by doing the whole "fastboot oem unlock unlock code" then the "fastboot oem lock" ... I'll look more into it but from what little I read it looks like it can not be unlocked again with out the Motorola unlock code...
We cannot teach people anything; we can only help them discover it within themselves.
ezknives said:
From what I was able to locate status code 2 indicates that the bootloader has been unlocked and relocked like by doing the whole "fastboot oem unlock unlock code" then the "fastboot oem lock" ... I'll look more into it but from what little I read it looks like it can not be unlocked again with out the Motorola unlock code...
We cannot teach people anything; we can only help them discover it within themselves.
Click to expand...
Click to collapse
Same here, I can see what it means but cannot find any way to get back to code 3 other than using the unlock code from Motorola, which I am unable to obtain because it says I am not eligible. Surprising that someone hasn't cracked the unlock code yet or made a keygen, people are so eager to do it with pirated computer software before the software is even released.
I've read of someone getting locked status code 2 b4 from flashing an older gpt with rsd (if I remember correctly) I think all that was required to fix it and get unlocked again was to flash the latest gpt. Very important..... Are you sure when you were unlocked you didn't ota update to .15? Because flashing .10 gpt while on .15 may be what caused your false relock
Nope, no OTA update to .15. The ZIP I have of the rom does include the gpt.bin file with the same timestamp as all the other files. I suppose I could try reflashing the whole rom once again later...
Hmm strange, I went to find the old thread I read about the gpt relock issue but it's not exactly the same as your situation.
http://forum.xda-developers.com/showthread.php?p=51436123
Until now I didn't think relock was possible due to the way unlocking works. It's a physical change, a qfuse was blown when the motopocalypse apk was run the first time. It can't be unblown lol. Wish I knew what went wrong here.

[Solved] How to Re-lock Bootloader and go back to stock?

Hello,
I want to relock the bootloader and go back to stock.
I tried flashing stock firmware using fastboot.
fastboot oem lock begin
flashed stock firmware
fastboot oem lock
But Bootloader is still unlocked.
I got message as first flash full stock system. Something like that. Don't remember as I tried this a week ago.
Any help will be highly appreciated.
Thank you in advance.
Edit : I also tried the Windows tool provided by one of the members but it failed too.
I used the same to unlock in the first place.
I think it depends on what you want to achive. While you might be able to re-lock the bootloader (which means it can't be flashed without being unlocked again), you will never ever get rid of the unlock message again. This - to my understanding - is an efuse which is permanently set. If you want to remove the unlocked bootloader boot message, I'd stay unlocked and would just flash a different boot logo (logo.bin) where the unlocked gfx are replaced with the standard gfx thus showing the standard boot logo.
I would like to relock the bootloader altogether.
I don't think you can. You can lock it but you can't remove the warning that it has been tampered with.
I don't care about the warning.
I just want to re-lock it.
Flashing the Official firmware for my Country - India did the job.
Last time I tried with firmware for ASIA.
I don't see any reason for that to fail but you never know.
Thanks for replying.
hey can you give me the link for that rom im also using the indian version but unable to lock the bootloader

Re-locking bootloader on pixel 4

Hi! I am flashing AOSP on a pixel 4 and pixel 4a device, but once after flashing the AOSP into the device, it works fine until the device is in flashing unlock state but when I tried to re-lock the bootloader, the pre-installed AOSP would not load and the device shows error "Invalid OS" failed to load OS.
Can you guide me on how to re-lock after flashing especially in pixel 4 and 4a devices?
Attached below is the issue I'm facing right now
Waiting for your response.
Thank You
Re-locking the bootloader forces it to boot into pre-installed ROM.
jwoegerbauer said:
Re-locking the bootloader forces it to boot into pre-installed ROM.
Click to expand...
Click to collapse
HI! Thank you for your valuable suggestion but the problem I am facing is that when I flash the AOSP into the device specifically pixel 4 and pixel 4a, it works properly in flashing unlock state but when I try to re-lock the bootloader with the command "fastboot flashing lock", the device will not load the pre-installed OS and show an Invalid OS error.
Could you help me out in this scenario?
You didn't get it for whatever reason.
The pre-installed OS got removed - means overwritten by the one you flashed.
UsamaBinAmir said:
Hi! I am flashing AOSP on a pixel 4 and pixel 4a device, but once after flashing the AOSP into the device, it works fine until the device is in flashing unlock state but when I tried to re-lock the bootloader, the pre-installed AOSP would not load and the device shows error "Invalid OS" failed to load OS.
Can you guide me on how to re-lock after flashing especially in pixel 4 and 4a devices?
Attached below is the issue I'm facing right now
Waiting for your response.
Thank You
Click to expand...
Click to collapse
If you want to lock the bootloader, but not run stock OS, you can try Graphene OS. https://grapheneos.org/
The bootloader lock checks to see if the operating system has been modified. By flashing anything other than official Google firmware (ie factory images/full ota) you fail those checks.

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