I have looked through a lot of threads before I decided to start this one with my issue.
my friend flashed the S3 from 4.1.2 to 4.2.2, so then I flashed it to 4.3 (BTU-I9300XXUGMK6)
It worked, but with lots of issues like some apps doesn't work, and random restarts.
So I decided to downgrade back to 4.1.2 with Odin, and guess what? I got stuck in a loop with Samsung Galaxy III screen. so i went into recovery mode to reset/factory restore setting and nothing happened.
So I tried installing another version of 4.1.2, and now I'm stuck at the installing loop, where the android has a cube thingy rotating in the stomach, then goes back to Samsung Galaxy III screen and repeat. It looks like as if the phone is trying to install the firmware, but it restarts before it happens?
Interesting thing is that I can get into download mode, but thats it.
Another thing is when I tried to flash it back to 4.3, everything in Odin was a success and when the phone starts to reboot and install...there is a green robot lying with exclamation mark and then reboots and repeats.