Hey I've seen this issue too, one of my friends has a GT I9192 and I updated his phone to the latest stock ROM first it worked very good, but one day he was recording something with his camera, and then played the recording after that the phone shut down, and didn't want to restart after taking the battery out and trying again and again, it reboots and after 3 or 4 min turns off again. I flashed some other stock roms but nothing, when I get in recovery mode, after some minutes the screen goes all blue.
And sometimes when restarting it shows colored lines in screen.
Went to Samsung Costumer Care (Saudi Arabia) they say that the phone has been rooted (which is not true) cause the KNOX Warranty bit shows 0x1
I don't know what to do.
The phone was bought in Saudi Arabia. And I live in Europe
Could I send it somewhere in Samsung CS in Europe cause i heard that here in Europe the KNOX warranty bit doesn't affect hardware damages (which I think that this issue is a hardware damage)