Downgrade Bootloader - Galaxy S6 Edge+ Q&A, Help & Troubleshooting

Guys, I'm on the latest bootloader (OL2) and want to flash a different rom. This rom requires and older bootloader (OJ5).
Is it safe to downgrade to the earlier one? I know problems occur flashing bootloaders from older Android versions but both are 5.1.1.
I have made a nandroid backup, but not sure if this is enough if the downgrade fails so thought i would ask first.
Cheers peeps

Well for those interested, I took a risk and tried it anyway and can confirm that you can downgrade the bootloader.

Related

Is there flashable bootloaders

Are there flashable bootloaders for Jb or KK?
No. Why would you want to mess with the bootloader? It's locked and can't be tampered with.
I have an unlocked G2 and rooted and since it is unlocked I am assuming it is an unlocked bootloader as well, just because if you use a JB ROM and you have a KK bootloader, you might have a working ROM but you encounter little errors and well that is where I am in and they become annoying, such as the com.android.systemui keeps going off sometimes and other numerous app problems also read and write problems to and from phone.
Now if I can flash a JB bootloader and re-install my JB ROM I would not encounter such problems.
Flash a JB stock KDZ and you should be fine.

how to downgrade from lollipop to jellybean?

Can it is possible? I have official firmware of jellybean dwnlded from sammobile.
Help.!
Not possible as the Knox-enabled bootloader prevents downgrades. Even if you were able to downgrade, say by perhaps not downgrading the bootloader while downgrading everything else, it's unlikely the radios on the device will ever function. About the only use there is for such a downgrade is to carrier unlock the S4 using RegionLock Away, and even then you only have to flash a modem to do that.
Downgrading to Android 4.4.2 should be possible, if you really want to. I'd recommend flashing a custom ROM instead. All the custom ROMs, regardless of whether they are Touchwiz-based, GPE-based or Cyanogenmod-based, all include the battery drain bugfix that stock ROMs lack.
Thanks but i dont want now bcz voltaqe kernel has solved my problem i.e sound gain
Excellent! Good to hear you got things resolved.

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a custom ROM then had to flash to stock ROM to be able to flash to another custom ROM--however, I accidentally flashed a newer version of the AT&T stock ROM which locked my bootloader and I could no longer flash to a custom ROM).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.

G900V from 4.4.4 to most current version with root?

Looked thru the other threads, and didnt see anything that pertained directly perhaps someone can point me in the right direction.
Have my stock S5 from verizon, on 4.4.4 NK2 firmware. Looking to update to whatever is the most current stock firmware with root. I'm coming to this from years of rooting Sprint devices, this is my first Verizon and I've been putting it off forever. Been getting the nag screen everyday now for a software update and I figured it was the time to update this and get myself root.
Thanks in advance for any help in where to look. Please forgive me in advance if this is a duplicate, I searched...I really did, but since its all new to me I wanted to ask.
Looks like the process is to flash 4.4.2, root, check if bootloader can be unlocked, and then proceed 2 different ways if it can be dev bootloader unlocked. If it can, unlock bootloader, flash twrp, and then flash whatever rom you want. If you can't unlock the bootloader, folow the guides to upgrade keeping root with safestrap and use roms that are TW for locked bootloaders. Someone correct me if I'm wrong. I just got a 4.4.4 g900v myself in a trade and I'm figuring out how to proceed as well.
Ok, slight difference. You can root & check the bootloader from 4.4.4...
Root here (Using NCG stock kernel...
http://forum.xda-developers.com/ver.../safely-upgrade-root-4-4-4-nha-volte-t2879348
If you're having trouble finding the NI2 kernel like I did it's here...
http://forum.xda-developers.com/showthread.php?t=2784880
Then use the method bootloader unlock from method 3 here...
http://forum.xda-developers.com/ver...t/rd-unlocking-galaxys-s5-bootloader-t3337909
If you can unlock your bootloader (I could), then flash the bootloader of choice from that link above to correspond to the rom you want. I'll be trying out Phoenix with pd4 (installed from above link) from here...
http://forum.xda-developers.com/verizon-galaxy-s5/development/port-phoenix-rom-v12-0-t3400292

I have upgraded my phone(sm g935a)to Oreo i want to downgrade it

Kindly guide me someone i want to downgrade to marshmallow on SM G935A .. i have tried the apk1 rom but failed to flash please help...
You'll get used to Oreo, it's pretty good so far.
Assuming it's still on bootloader 4, you can downgrade to any firmware build using BL4. I don't recall off the top of my head if there was ever a MM build that used BL4, but that's the restriction. Anything else will either not flash or brick your device. You will need a modded version of ODIN to do the downgrade.
why do you want to downgrade?

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