[Q] Downgrading CM11 to stock 4.3 on i747M

Mzrz · Jun 10, 2014

I know there are a few threads regarding this issue but I can't seem to find a definitive answer.

I am currently running stock 4.3 jellybean (rooted). My phone hasn't received the 4.4 KitKat update yet, so I wanted to install CM11 in order to get KitKat on my s3. However, I heard CM11 can be buggy on the s3, so in case things go south, I want to be able to revert back to the stock 4.3 rom. Some people have said that you can easily flash the stock ROM via ODIN. However, others said that downgrading from 4.4.2 to 4.3 will hard brick the device since installing CM11 updates the boot loader. So downgrading to 4.3 stock with a 4.4.2 boot loader will cause a hard brick according to other threads I've seen. My question is, how can I downgrade from CM11 to stock 4.3 safely without bricking? Thanks in advance.

audit13 · Jun 10, 2014

If you are sure you are using a Canadian version of the i747m, you can flash back to stock in Odin using a stock 4.3 ROM for the phone's original carrier (Bell, Rogers, Telus).

Mzrz · Jun 11, 2014

audit13 said:
If you are sure you are using a Canadian version of the i747m, you can flash back to stock in Odin using a stock 4.3 ROM for the phone's original carrier (Bell, Rogers, Telus).

Yes I got the phone from Rogers, it's most definitely i747M. But do I have to worry about any issues with the bootloader? I'm assuming installing CM11 will install the 4.4.2 bootloader, so if I choose to downgrade to the stock 4.3 rom, will it cause any issues seeing as I'm running a 4.3 rom with a 4.4.2 bootloader? I just want to make sure because I heard it can cause some serious problems if the bootloader is newer than the rom.

audit13 · Jun 11, 2014

Mzrz said:
Yes I got the phone from Rogers, it's most definitely i747M. But do I have to worry about any issues with the bootloader? I'm assuming installing CM11 will install the 4.4.2 bootloader, so if I choose to downgrade to the stock 4.3 rom, will it cause any issues seeing as I'm running a 4.3 rom with a 4.4.2 bootloader? I just want to make sure because I heard it can cause some serious problems if the bootloader is newer than the rom.

I have never come across a custom ROM that touches the bootloader. A compatible bootloader has to be loaded on the phone before you attempt to install the custom ROM. Supported bootloaders can be found in the ROM's updater script.

I assume your phone has no warranty since you rooted it on stock 4.3. Did you root it by installing a pre-rooted ROM?

You could copy a ROM to your external SD card, install Philz Touch via Odin, reboot directly to recovery, create a nandroid backup, wipe cache, Dalvik, data, and install your KK ROM.

Mzrz · Jun 11, 2014

audit13 said:
I have never come across a custom ROM that touches the bootloader. A compatible bootloader has to be loaded on the phone before you attempt to install the custom ROM. Supported bootloaders can be found in the ROM's updater script.

I assume your phone has no warranty since you rooted it on stock 4.3. Did you root it by installing a pre-rooted ROM?

You could copy a ROM to your external SD card, install Philz Touch via Odin, reboot directly to recovery, create a nandroid backup, wipe cache, Dalvik, data, and install your KK ROM.

Okay, I was just making sure because I know OTA updates can change the bootloader, so I just wanted to make sure the custom roms don't do that. As for the custom recovery, are you recommending Philz Touch over CWM and TWRP? Do you know which custom recovery is installed from the CM installer?

Mzrz · Jun 11, 2014

audit13 said:
I have never come across a custom ROM that touches the bootloader. A compatible bootloader has to be loaded on the phone before you attempt to install the custom ROM. Supported bootloaders can be found in the ROM's updater script.

I assume your phone has no warranty since you rooted it on stock 4.3. Did you root it by installing a pre-rooted ROM?

You could copy a ROM to your external SD card, install Philz Touch via Odin, reboot directly to recovery, create a nandroid backup, wipe cache, Dalvik, data, and install your KK ROM.

Oh and one more question, my phone was originally carrier locked to Rogers and unrooted on 4.3 jelly bean. I brought it in to a cell store for them to carrier unlock it for me, but they used a rooting method to unlock it (because SuperSU was installed on it when I brought it back). They didn't unlock it with a code, so I'm guessing they used something like Samsung Tool or z3x shell. If I install CM11, will I lose the unlock, considering it's more of a "soft unlock", or is the unlock permanent regardless of how many roms I flash? Thanks for your help!

audit13 · Jun 11, 2014

Mzrz said:
Okay, I was just making sure because I know OTA updates can change the bootloader, so I just wanted to make sure the custom roms don't do that. As for the custom recovery, are you recommending Philz Touch over CWM and TWRP? Do you know which custom recovery is installed from the CM installer?

Philz is based on the latest release of CWM and I prefer CWM over TWRP because I had problems flashing ROMs. Once I switched to Philz/CWM, no more problems.

Mzrz said:
Oh and one more question, my phone was originally carrier locked to Rogers and unrooted on 4.3 jelly bean. I brought it in to a cell store for them to carrier unlock it for me, but they used a rooting method to unlock it (because SuperSU was installed on it when I brought it back). They didn't unlock it with a code, so I'm guessing they used something like Samsung Tool or z3x shell. If I install CM11, will I lose the unlock, considering it's more of a "soft unlock", or is the unlock permanent regardless of how many roms I flash? Thanks for your help!

The unlock should be permanent. I unlocked it using the free method when on 4.1.1 and no ROM has ever caused it to re-lock. Reflashing a completely stock ROM, including the bootloader, did not relock the phone.

Please remember that flashing and changing ROMs will always carry a risk of soft bricking or hard bricking your phone. Make sure you read all of the guides and be prepared for disaster.

Good read here: http://xdaforums.com/showthread.php?t=2201860

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