And If you try and successfully please report here and let me know if it works 100% on another S3.
After flashed stock XXELLA rom or flash new XXELLA bootloader. You can't not flash back to old previous version of bootloader anymore via PC Odin. And after every S3 reboot, it will show red exclamation mark at boot logo and always check flash counter =1 in download mode if you user custom kernel or custom CWM. This is 3 method to flash back to old bootloader:
>>> METHOD 1: You can use Sboot Checker to check which bootloader is backlisted. Then use some basic terminal commands to downgrade your bootloader. This is more simple and safer. Please visit @Odia's topic http://forum.xda-developers.com/show....php?t=2081748. Credit to him.
>>> METHOD 2: This is the most simple and fast method for lazy guys ! Just download the following .zip file and flash via CWM Recovery. You will be restored to old ICS bootloader XXBLFB. This is download link http://forum.xda-developers.com/show...&postcount=105. Credit to @fbatti73 he has ported @Odia's command to CWM flashable zip file. So many thanks to @fbatti73 and @Odia.
>>> METHOD 3: This is the first method I've found but far too much work involved and take alot of time. But if you like this' also another choosing:
1. Always backup first, full wipe yor S3 and flash back to lastest stock ICS 4.0.4 rom not included old bootloader in it or you can fash via Mobile Odin and don't care it include a bootloader or not because Mobile Odin doesn't flash bootloader. I''m in Vietnam and I choose this ICS 4.0.4 rom I9300XXBLH1_I9300OLBBLH1_XEV.zip http://www.hotfile.com/dl/166926386/...1_XEV.zip.html
2. After flashed ICS 4.04 rom don't root or do another work on it, Just check OTA update on S3 by Go to Settings > About device > Software update > Click Update. Let OTA update your S3 to JB 4.1.1. In my case the OTA will update to JB 4.1.1 XXDLJ1 and it takes about 2xx MB size. Yes, it's here. The processing of OTA update from ICS 4.0.4 to JB 4.1.1 can break the protect of new bootloader XXELLA . And after OTA updated to JB 4.1.1 you would have the old version of JB 4.1.1 bootloader. In my case it's bootloader XXDLJ1.
3. But although our S3 has old bootloader XXDLJ1 but it's still a JB bootloader version. Every S3 reboot you will still get red exclamation mark and counter =1 if you use custom kernel or custom CWM. To make red exlamation mark and counter =1 disappear totally. You only have to flash back to old ICS version bootloader XXALEF. And now you can flash back to XXALEF bootloader via PC Odin.
4. Just install a custom kernel and a custom CWM Recovery. Wa wa, red exclamation mark and counter =1 have already dissapeared totally.
This is the link of ICS old bootloader XXALEF can flash via Odin: http://www.mediafire.com/?dlruvz9fib6c046
>>> Many thanks to XDA members of the following threads. Yours'' replys helped me accidental found this way )