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[Q] i337 - ATT - bootloader

Hi trying to understand whether i can install custom ROM or not. I have i337ucufni1 baseband and according to terminal emulator i have the same bootloader (NI1)? How do I know if this is a locked bootloader or not so I can Root/Install custom ROM?/
Please advise,

Locked Bootloader
hol64 said:
Hi trying to understand whether i can install custom ROM or not. I have i337ucufni1 baseband and according to terminal emulator i have the same bootloader (NI1)? How do I know if this is a locked bootloader or not so I can Root/Install custom ROM?/
Please advise,
Click to expand...
Click to collapse
It is locked. But with safestrap it can be unlocked and rooted with Towelroot. A custom rom can be tricky as it must you Touchwiz same as stock firmware. Maybe someone else can give you more details.

Just to add on to TailGunner. They are all locked but the early bootloaders, of which you are not, can use an exploit called loki-doki to bypass Sammy's security checks.
Start here--
http://forum.xda-developers.com/galaxy-s4-att/general/summary-rooting-roming-i337-t2872013
You will need SafeStrap, no custom recoveries, kernels etc.
Read carefully so as not to brick anything.
Oh, BTW MODS will move this to Q&A--
Good Luck--:good:

All you need to know http://forum.xda-developers.com/showthread.php?t=2616221

OK2, Android 5.0.1--what are my options?

I currently have AT&T stock (I used to have a custom ROM then had to flash to stock ROM to be able to flash to another custom ROM--however, I accidentally flashed a newer version of the AT&T stock ROM which locked my bootloader and I could no longer flash to a custom ROM). I updated my AT&T stock ROM recently and now my back/menu buttons don't work, so I want to see if I can flash to a custom ROM now.
I don't remember the procedure to flash a custom ROM--do I first need to get root in order to unlock the bootloader to be able to flash ROMs (i.e. if I have root then I am guaranteed to be able to unlock bootloader in order to flash ROM)? Is the baseband version the only thing that determines whether I can unlock the bootloader and then be able to flash ROMs?
I currently have OK2 as broadband version and checked one of the stickied threads which said this:
" ROOT
OK2 -- No direct root method. Must Odin OC4 kernel, use Kingroot, then Odin OK2 kernel back."
Does that mean what I have to do is use Odin to get OC4 kernel, then use Kingroot, then Odin OK2 kernel and then I will be able to have root, which means I can then unlock my bootloader and be able to flash to ANY ROM (not just TouchWiz-based ROMs)? Is there anything else I need to consider or is this 100% foolproof? In the future, what should I be careful of in order to prevent getting my bootloader locked again--just that I don't flash a stock (AT&T) ROM that is known to lock back the bootloader?
Thank you all!

There's no way to unlock the bootloader if you have updated your device to the lastest firmware version. The only thing you can do is flash SafeStrap and use Stock Kernel Based ROMs which are compatible with Safestrap.
As regards to the procedure of rooting an OK2 firmware, I'm afraid I won't be able to help you.
Have a happy new year.

mindstormer said:
...however, I accidentally flashed a newer version of the AT&T stock ROM which locked my bootloader ...
Click to expand...
Click to collapse
I was just about to sit down and flash a stock ROM. Can you explain what you mean by this? Did you flash OK2 and it caused you a problem?

smock9 said:
I was just about to sit down and flash a stock ROM. Can you explain what you mean by this? Did you flash OK2 and it caused you a problem?
Click to expand...
Click to collapse
It was a while ago but I used to have I believe an MDL broadband version which meant I could flash any ROM available. I tried a different ROM, didn't like it, then decided to flash back to the stock ROM but accidentally flashed a newer version of it, which meant that my bootloader is now locked. With a locked bootloader, apparently I can only flash to a newer stock ROM (not other ROMs like Cyanogenmod) via Safestrap.
I think if you don't have the MDL broadband version you shouldn't worry about it anyway because it is locked and you will only be limited to flashing stock ROMs.

Slight correction
The previous entry is not entirely correct. Like the OP, I was originally on an unlocked bootloader on my i337. I'd purchased my i337 on the first day and eschewed OTA updates. I wanted to try a touchwiz based ROM, Hyperdrive, and in doing so I recall flashing the stock NB1 firmware. Every firmware beginning with NB1 has a locked bootloader and there has been no progress for more than a year in unlocking the bootloader again. This can limit you to either stock ROMs OR other touchwiz based ROMs like Hyperdrive. I love the Hyperdrive ROM (now on release 21) but its developer has moved on to a newer phone, so it's stuck at Android 4.4.2 and no one has picked up the project in many months. There are several other touchwiz based ROMs for the i337 version of the S4 which I have also tried but I prefer Hyperdrive's myriad customization, even without proper patching. I'll be moving on soon to the Nexus 6P as my daily driver, but would very much like to keep my S4 up to date with a custom ROM. Given the number of people that have been in this same situation, where a newer stock ROM from AT&T locked a previously unlocked bootloader, it's been surprising that the issues have not been overcome on a phone as popular as the Galaxy S4 was and continues to be. I've seen unlocked versions of the S4 selling for just under $400 in the last week of 2015.

Use the desktop version of Kingoroot to root and use Super su and update the binary. Don't forget to hit thanks if this helped.

The bootloader for the at&t s4 was never unlocked. The MDL bootloader had a flaw in it that allowed you to use LOKI which is a lock bypass, not a way to unlock the bootloader.

how can i figure out the oldest rom i can downgrade to?

now i am on optimal 15-5

If You Are Rooted And Bootloader Unlocked You Can Get NI2 ROM At Least That's The Earliest I Have Gone But There Is More Than Likely An NCG ROM Out there somewhere download links don't work anymore is my main issue I have run into
you can get NCG stock firmware installed by going to brens123 guide I booted NCG on pb1 bootloader on xda under s5 Verizon forum whether you have bootloader unlock or not
you have to have root though and supersu installed

thanks i dont have unlocked bootloader wrong chip.

Using an S4 as emergency phone, and I need slight guidance for rooting & recovery

Hello
My LG V10 came across the famous bootloop issue, and I shipped it to LG. In the meantime, I am using an old S4 that was saved for emergencies like this one. It is running 4.4.4, I337UCUFNJ4, and I rooted it with Kingoroot.
I understand that it should OTA to 5.1 in pronably a day or 2 if I check for a software update; it sat turned off since 2014, so it did not receive anything.
1. Do I OTA and reroot?
2. Can I manually jump to 5.1?
Ultimately, I would like to install TWRP and the Blissrom or some other ROM, but I don't want to take an OTA that may screw me up for later. I read that there's a loki thing that will prevent future installations of recovery or something like that. I realize that I will be using a short time (2-3 weeks), but I would like to leave it rooted and with a good ROM.
Thank you

The bootloader is locked so that means TWRP cannot be flashed to the phone and the phone will only run custom ROMs based off a stock Samsung ROM.
OTA updates will not work if the phone is rooted.

audit13 said:
The bootloader is locked so that means TWRP cannot be flashed to the phone and the phone will only run custom ROMs based off a stock Samsung ROM.
OTA updates will not work if the phone is rooted.
Click to expand...
Click to collapse
I'm confused or perhaps you are misinformed. I have seen a lot of ROMs for this device including Blissrom and many others. All od them get flashed through twrp or Safeway or aome name like that.

You mean safestrap?
Maybe you are thinking of the non-AT&T models of the s4 that work with custom ROMs such as Lineage and Validus. Only the AT&T version of the s4 has a locked bootloader, starting with Android 4.3 and up.
There has never been an sgh-i337 s4 with a locked bootloader than can run TWRP. Same goes for the AT&T sm-n900a note 3 with a locked bootloader.

audit13 said:
You mean safestrap?
Maybe you are thinking of the non-AT&T models of the s4 that work with custom ROMs such as Lineage and Validus. Only the AT&T version of the s4 has a locked bootloader, starting with Android 4.3 and up.
There has never been an sgh-i337 s4 with a locked bootloader than can run TWRP. Same goes for the AT&T sm-n900a note 3 with a locked bootloader.
Click to expand...
Click to collapse
But there's a forum dedicated to AT&T development full of roms here on xda.

Yes, there is a full section but you need to look at the ROM requirements. Some of these ROMs were developed before AT&T pushed out an OTA update that locked the bootloader. Other ROMs are made for the non-AT&T s4 such as the sgh-i337m and gt-i9505.
You will not see any ROM that is not based off a stock Samsung ROM that can be installed onto an AT&T s4 that has a locked bootloader. Also, you will not see any version of TWRP/CWM/Philz that can be installed onto an AT&T s4 that has a locked bootloader. Same goes for the AT&T sm-n900a.
I understand your skepticism and appreciate your posts as we are all here to learn from each other.
https://forum.xda-developers.com/showthread.php?t=2785166
https://forum.xda-developers.com/galaxy-s4-att/help/ez-unlock-bricked-phone-galaxy-att-s4-t3703235
https://forum.xda-developers.com/galaxy-s4-att/help/help-installed-chainfire3d-phone-doesnt-t3700830
https://forum.xda-developers.com/galaxy-s4-att/help/samsung-galaxy-s4-sgh-i337-ok2-locked-t3458353

Thanks for the clarification. So how do I know if my bootloader is locked? If I took that ota update that messed things up?

The bootloader becomes locked when the phone is updated to Android 4.3 or newer. I think it needs to be on the MDL bootloader to be unlocked. Anything beginning with an "N" or "O" means that the bootloader is locked.

Thanks audit. And I assume that there's no way to go backwards to a pre-4.3 rom and unlock that bootloader.
So. I'm on 4.44 rooted. Do i remove root and take any ota and reroot? I guess that I'll settle for going as high as possible with the stock rom but rooted with the ability to disable some of the bloatware.
How can I proceed?
In those links that you mentioned, it states that we can flash debloated TouchWiz roms that might be better than stock. Is that right? So can I do that?

You will need to install safestrap to flash a custom ROM. The debloated ROMs must be based off a ROM that is designed for the AT&T s4.
I recommend reading through this thread: https://forum.xda-developers.com/showthread.php?t=2616221

Audit... I odined back to nb1, rooted, and used flashify to get to rooted stock oc3.
How can I get to ok3? And should I leave ota services frozen so as to not ruin and loose root?

OTA will not work with a rooted phone.
Maybe this will help: https://forum.xda-developers.com/showpost.php?p=56453108&postcount=2
I don't have an sgh-i337 so I can't tell you how to get back to a completely stock ROM to get OTA updates. I have the sgh-i337m which is the Canadian version of the s4 without a locked bootloader.

I wrote a guide and FAQ revolving around the MDL bootloader here (if anyone cares to read it):
https://forum.xda-developers.com/galaxy-s4-att/general/how-to-one-guide-to-mdl-bootloader-t3584122

[Q] Can I use Lineage OS 15.1?

I have a question since I watched the youtube video on how to upgrade my phone samsung s4 at&t to Oreo, but I read that I need a bootloader. Then when I read articles here in xda, mostly says that this phone can't be unlock? so How do I deal with this? Please explain simply because I am new in this.

If the phone is running an MDL bootloader, it may be possible to flash Oreo. If the phone is running a newer bootloader, the phone can only run TWRP and will not run Nougat or Oreo.

hjayc24 said:
I have a question since I watched the youtube video on how to upgrade my phone samsung s4 at&t to Oreo, but I read that I need a bootloader. Then when I read articles here in xda, mostly says that this phone can't be unlock? so How do I deal with this? Please explain simply because I am new in this.
Click to expand...
Click to collapse
You cannot unlock the bootloader. However, if you're on the MDL bootloader then you can use an exploit called loki doki to install a custom recovery and a custom ROM. If you're on a newer bootloader other than MDL, then you are stuck with only booting custom touch wiz based ROMs and must use safe strap if on kit kat or flash fire if on lollipop.

Can you oden back to mdl if you are running NJ4.
does it matter id i upgraded to Kittkatt with a custon rom vs ota update on if the bootloader got locked? does goldeneye kittkatt 4.4.4 lock the bootloader?

cousindan said:
Can you oden back to mdl if you are running NJ4.
does it matter id i upgraded to Kittkatt with a custon rom vs ota update on if the bootloader got locked? does goldeneye kittkatt 4.4.4 lock the bootloader?
Click to expand...
Click to collapse
No you cannot odin back to MDL, if you try you will brick your phone. It doesn't really matter how you update given your bootloader is locked (unless you're on the MDL firmware). Golden eye ROM does not lock the bootloader, no custom ROMS lock the bootloader.