MJB bootload How to tell if a rom is safe - AT&T, Rogers, Bell, Telus Samsung Galaxy S III

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

Related

Can you downgrade bootloader?

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.

[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.

Help with gs3 root

Hey guys. This may have been asked already but i am coming from verizons gs4. and over there you can oly get custom recovery if youre on mdk bootloader.
I just bought this phone for my brother and it came with 4.12 (MG2)
I see everywhere that people were able to get 4.3. i tried updating through phone and through kies and says its up to date. so now my question i guess is what bootloader do i need to be on or what 4.x.x do i need to be on in order to root and get custom recovery to flash custom roms?
any help will be greatly appreciated.
I recommend not updating to stock 4.3 ROM as this will install Knox and you will have a non-downgradeable bootloader. You can use Odin to flash Philz Touch which is based on CWM. From there, you can flash custom ROMs.
Some ROMs require a 4.3 bootloader, but these would tend to be based on the stock Samsung ROM. I am running the latest Validus 4.4.2 on a stock Bell 4.1.2 bootloader without a problem.
audit13 said:
I recommend not updating to stock 4.3 ROM as this will install Knox and you will have a non-downgradeable bootloader. You can use Odin to flash Philz Touch which is based on CWM. From there, you can flash custom ROMs.
Some ROMs require a 4.3 bootloader, but these would tend to be based on the stock Samsung ROM. I am running the latest Validus 4.4.2 on a stock Bell 4.1.2 bootloader without a problem.
Click to expand...
Click to collapse
Oh ok. Well I just succesfully rotted and installed latest touch cwm.
so if I stay on 4.1.2 I can basically flash any kitkat roms? Because I dont want to install a tw rom.
So another question what are some good 4.4 kk roms? As in stable for daily use that I could flash
Sent from my SCH-I545 using XDA Premium 4 mobile app
Most kitkat ROMs will work with a 4.1.2 bootloader based on my experience.
I like the Ground Zero ROMs and use them on the s3, Moto Atrix HD, and Nexus 4.
http://forum.xda-developers.com/showthread.php?t=2550340

MJB Bootloader and Modem question

Installing the MJB Official bootloader and modem, can we still install custom aosp roms?
You should have no problem installing custom ROMs. I have an i747m with a 4.1.2 bootloader and have loaded a few KK ROMs with no problem.
Yea you shouldn't have any problem installing Roms on mjb just make sure that the ROM you install does not install a downgraded bootloader or you will brick the device......also if a ROM uses the ne4 bootloader you will be stuck using the ne4 modem
No rom should ever include anything but the system and kernel imo. Ive personally never run into one that includes the firmware/bootloaders, but if you do you should bring it up to the dev.

Rom selection

Ive been searching for awhile now but at work is my only time to do so and time is limited.. I am searching for a rom to run with ucdmg2 bootloader. I'm not really feeling up to updating the bootloader using odin.
hatchguy06 said:
Ive been searching for awhile now but at work is my only time to do so and time is limited.. I am searching for a rom to run with ucdmg2 bootloader. I'm not really feeling up to updating the bootloader using odin.
Click to expand...
Click to collapse
Do you have a custom recovery installed?
You didn't say, but I can infer that you have an i747 and not an i747M based on the MG2 bootloader.
Without a custom recovery you are stuck using Odin to get a custom recovery in order to flash anything other than a stock rom. There are recovery flashable bootloader and modem files for 4.3 and newer bootloaders and modems.
With the 4.1.2 bootlaoder and modem you could run Jellybean roms from CM ( CM10.x ) or those based on CM or AOSP. There may be a few AOSP bassed on KitKat you could use, but it would probably be a version that is more than a year and a half old. Anything newer will need a 4.4.2 bootloader.
dawgdoc said:
Do you have a custom recovery installed?
You didn't say, but I can infer that you have an i747 and not an i747M based on the MG2 bootloader.
Without a custom recovery you are stuck using Odin to get a custom recovery in order to flash anything other than a stock rom. There are recovery flashable bootloader and modem files for 4.3 and newer bootloaders and modems.
With the 4.1.2 bootlaoder and modem you could run Jellybean roms from CM ( CM10.x ) or those based on CM or AOSP. There may be a few AOSP bassed on KitKat you could use, but it would probably be a version that is more than a year and a half old. Anything newer will need a 4.4.2 bootloader.
Click to expand...
Click to collapse
Yes I'm running the newest cwm recovery at the moment. so I guess ill track down a cm10 rom ..
hatchguy06 said:
Yes I'm running the newest cwm recovery at the moment. so I guess ill track down a cm10 rom ..
Click to expand...
Click to collapse
If you haven't found one yet, check here: https://download.cyanogenmod.org/?device=d2att&type=snapshot
Don't forget GApps.

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