Can you downgrade bootloader? - AT&T, Rogers, Bell, Telus Samsung Galaxy S III

I am thinking to flash a 4.4 ROM on my S3 I747M. The only thing I am worried about the bootloader. If I flash the latest boot loader can I downgrade it?
Here a scenario
I am on 4.4 kitkat,with the latest bootloader,and I decide to go back to 4.2.2 with the latest bootloader. Is it possible to do that?

xXFl4sh said:
I am thinking to flash a 4.4 ROM on my S3 I747M. The only thing I am worried about the bootloader. If I flash the latest boot loader can I downgrade it?
Here a scenario
I am on 4.4 kitkat,with the latest bootloader,and I decide to go back to 4.2.2 with the latest bootloader. Is it possible to do that?
Click to expand...
Click to collapse
What carrier do you use? If AT&T is it the MJB bootloader.
You can check what bootloader you having using this - https://play.google.com/store/apps/details?id=org.freeandroidtools.root_checker
If you are on AT&T with the MJB bootloader you CANNOT downgrade the bootloader. It will brick the phone. My guess is that you could possible run a 4.2.2 ROM with the MJB bootloader. I have run 4.3 and 4.4 on the MG2 bootloader with no problem but haven't tried to run a 4.2.2 on the MJB bootloader. As long as the 4.2.2 ROM doesn't flash a bootloader, I would try it. But that's me. Just back sure to have a current backup. If there are any doubts about the 4.2.2 ROM flashing a bootloader, don't do it if on MJB.

xXFl4sh said:
I am thinking to flash a 4.4 ROM on my S3 I747M. The only thing I am worried about the bootloader. If I flash the latest boot loader can I downgrade it?
Here a scenario
I am on 4.4 kitkat,with the latest bootloader,and I decide to go back to 4.2.2 with the latest bootloader. Is it possible to do that?
Click to expand...
Click to collapse
most 4.3 aosp roms can run on the mjb bootloader but you have to modify the updater script to include it. but what the post says above if you try to downgrade the bootloader from mj2 ATT then it will brick the device

I have the MVLDLK4 bootloader. The only thing I am worried about is that there might be a few errors while using the ROM. I have tried about 3-4 4.2.2 ROMS but there is always 1 or 2 errors eg. Wifi does not work. Since there is only a few roms on 4.4+, i am worried I wont get a stable rom with minor error.
Cause If I update and the rom has errors, I have no backup rom.

Related

what AOSP based roms are compatible with MJB bootloader?

hi.
and thanks.
I have tried a few 4.4.2 ROMS and they all loaded on my 4.1.2 bootloader so I would assume they would load on your phone's newer bootloader.
If you're not sure, you can look at the ROM's updater script to make sure.
audit13 said:
I have tried a few 4.4.2 ROMS and they all loaded on my 4.1.2 bootloader so I would assume they would load on your phone's newer bootloader.
If you're not sure, you can look at the ROM's updater script to make sure.
Click to expand...
Click to collapse
are you or were you with MJB bootloader when tried 442 roms?
thanks
hormosapiens said:
are you or were you with MJB bootloader when tried 442 roms?
thanks
Click to expand...
Click to collapse
I don't recall which bootloader I had but I never had 4.3 on my phone; therefore, I never had Knox. I was able to load 4.4.2 ROMs with the stock 4.1.2 bootloader.
I know my bootloader is older than 4.3 because I was able to flash a stock 4.1.1 ROM onto my 4.1.2 ROM using desktop Odin. I unlocked my phone while on 4.1.1 and flashed back to stock 4.1.2. The stock ROMs from samfirmware include bootloaders and modems.

[q] 4.3 jellybean ota questions

I've got a Galaxy S3 I747 it is currently running 4.1.1, I747UCDLK3 Baseband. I'm not exactly a noob when it comes to flashing and rooting, I know my way around CWM and Odin pretty well. But I have a few questions on this 4.3 OTA. (I am a forum noob)
-Will I still be able to root? (I heard CF works for it)
-Can I install CWM? (Is the Bootloader locked??)
-Will I be be able to I flash other roms than the 4.3 TW like CM11Snapshot? (Is the bootloader locked?)
-What the h*ll is knox and why should I be worried?
-What is with the boot loader downgrading thing? (Have to do with locked bootloader??)
I AM NOT AT ALL WORRIED ABOUT A FLASH COUNTER OR VOIDING A WARRANTY I AM NOT ON A CONTRACT . I JUST DO NO WANT TO HARD BRICK MY PHONE.
If you take the OTA 4.3 update, it will install Knox and the 4.3 bootloader.
The 4.3 bootloader cannot be downgraded and attempts to do so will probably brick the phone.
You can root the stock 4.3 ROM with auto root but Knox may interfere with the process of cause issues after the fact.
You can still install CWM. I rrefer Philz Touch which is CWM-based.over TWRP.
So can I still flash roms?
Sent from my SAMSUNG-SGH-I747 using xda app-developers app
Yes, you can flash ROMs. Is your phone unlocked? Since you're on 4.1.1 stock, you can unlock it for free.
Personally, I avoided the 4.3 update because it installs knox and the 4.3 bootloader which can cause problems when using Odin to get back to stock.
I have a Canadian version of the s3 and I'm able to run KK ROMs with a stock 4.1.2 bootloader.
audit13 said:
Yes, you can flash ROMs. Is your phone unlocked? Since you're on 4.1.1 stock, you can unlock it for free.
Personally, I avoided the 4.3 update because it installs knox and the 4.3 bootloader which can cause problems when using Odin to get back to stock.
I have a Canadian version of the s3 and I'm able to run KK ROMs with a stock 4.1.2 bootloader.
Click to expand...
Click to collapse
Unlocked as in Bootloader? Yeah I've been able to flash roms via CWM and Odin on 4.1.1 and as in Carrier unlocked? Yes I use Straight Talk on this ATT S3
If I got the 4.3OTA I wouldn't need Odin to go back stock if I flashed a ROM would I? I could just make a back up via CWM then restore later if I wanted right rather than using ODIN?
See I can't use KK roms because I have the 4.1.1 BL so is there a way I can upgrade my boot loader to the 4.1.2 version??
Would I lose my carrier unlock if I upgraded to 4.3 or if I upgrade my bootloader??
I suggest downloading a ROM you want to try, then unzip the ROM and look at the updater script to see which bootloaders are supported. The updater-script file is located in \META-INF\com\google\android\updater-script. You can use a text editor to open the updater-script file.
The first few lines will list the bootloaders that are supported. I run Validus which is a KK ROM using a stock 4.1.2 i747m bootloader.
Do you know about this > "If I got the 4.3OTA I wouldn't need Odin to go back stock if I flashed a ROM would I? I could just make a back up via CWM then restore later if I wanted right rather than using ODIN?"
Also couldn't I just upgrade my Bootloader and Modem from here?
http://forum.xda-developers.com/showthread.php?t=2321310
http://forum.xda-developers.com/showthread.php?t=1831898
I feel like if I upgrade my boot loader then I won't have to worry about restrictions.
Would I lose my carrier unlock if I upgraded to 4.3 or if I upgrade just my bootloader??
I ended up flashing the MG2 Modem and Bootloader, I'm good now, also if I want 4.3 I saw loserskater has a leak version that will be good and wont not let me downgrade my bootloader.

MJB bootload How to tell if a rom is safe

SO I just got a s3 MJB bootloader I've been doing research and it seems like with this bootloader you can brick your phone if you install ROMs that mess with the bootloader. I was just wondering how you can tell if a rom going to flash a new bootloader?
By reading the description? If you're flashing a TouchWiz based ROM that is on 4.1.2 Jelly Bean, you can flash that only if you're NOT on the MJB bootloader. If you're on the MJB bootloader, you can only flash 4.3 TouchWiz based ROMs.
AOSP does not matter, at least to my understanding. You will more than likely need to upgrade CWM or TWRP if you plan on flashing AOSP KitKat ROMs. If you don't, you'll get an error when flashing that can only be resolved on the latest versions or CWM or TWRP.
Sent from my SAMSUNG-SGH-I747 using Tapatalk

Downgrading from 4.4.2 with NF2 Bootloader to 4.3 is it possible ?

i have stock 4.4.2 NF2 bootloader , what i need to do for change it to 4.3 ?
and is there any way to unlock hidden languages in 4.4.2 ?
Any attempt to downgrade the bootloader will cause a brick. You can, however, flash a 4.3 rom via custom recovery it will run on your current bootloader. Wifi may not work without using ktoonsez kernel though.
Sent from my SAMSUNG-SGH-I747 running TMS3KK-2.0

[Q] ND3 bootloader downgrade

I had to update to ND3 Kitkat bootloader in order to install Dr ketan's 4.4.2 V12 Rom. I still find my old 4.1.2 is much more faster and stable so I wanted to flash stock firmware but I couldn't because of the bootloader. So my question is, is it possible to downgrade the bootloader so I can use 4.1.2 again, flash mj5? If not are there things that I could try? Will there be a modified kitkat bootloader than I can install so I can downgrade?
Thanks
EmperorRedPanda said:
I had to update to ND3 Kitkat bootloader in order to install Dr ketan's 4.4.2 V12 Rom. I still find my old 4.1.2 is much more faster and stable so I wanted to flash stock firmware but I couldn't because of the bootloader. So my question is, is it possible to downgrade the bootloader so I can use 4.1.2 again, flash mj5? If not are there things that I could try? Will there be a modified kitkat bootloader than I can install so I can downgrade?
Thanks
Click to expand...
Click to collapse
Bootloader can't be downgraded. Flashing older bootloader might brick your phone.
With Mobile Odin Pro some people have successfully downgraded to 4.1.2, but bootloader remains intact.
Sent from my GT-N7100 using Tapatalk
EmperorRedPanda said:
I had to update to ND3 Kitkat bootloader in order to install Dr ketan's 4.4.2 V12 Rom. I still find my old 4.1.2 is much more faster and stable so I wanted to flash stock firmware but I couldn't because of the bootloader. So my question is, is it possible to downgrade the bootloader so I can use 4.1.2 again, flash mj5? If not are there things that I could try? Will there be a modified kitkat bootloader than I can install so I can downgrade?
Thanks
Click to expand...
Click to collapse
Doing it with software you may need hundreds of dollars worth of JTAG equipment with no guaranteed result. The cheapest and the most direct way is to have a repair shop to swap out the phone's EMMC, which should be under $100. Specifically state you want 4.1.2 and tell them NOT to upgrade the bootloader or ROM to 4.3 or later.

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