I have a Samsung GT-S7273T (Android 4.2.2) and yesterday something happened while I was sleeping. After that, the phone can't stay on for more than 30~50 seconds: it hangs and then restarts itself. I've noticed that any change I make to the phone is "reverted" after it restarts (like deleting a file or switching off Wi-fi). While it is on, everything works normally (facebook, watch videos in youtube, receive notifications, even play games, etc).
I've tried booting up in Safe Mode, same thing happens. I've also tried a data wipe/factory reset through recovery mode, but when I restart the phone, everything is just like before, as if no reset was made (although it says the the data wipe was successful). I've also tried a cache wipe only, but it gives an error and restarts itself when I try.
I've also noticed that if I try to restart the phone (hold power button, tap on "Restart" option), the phone starts to switch off, showing the "switch-off animation" and then stops there, instead of restarting (but it keeps working, even receiving notifications). After a few seconds, it hangs and then restarts (just like it normally does).
The phone is not rooted and I never downloaded any custom firmware or anything like that.
Is there any other way I can force a reset on my phone?
I've just tried to flash to stock ROM and then wiping data, but it seems to not have worked, although Odin reported success. All my files, apps and configuration are still there and the problem persists.
I've tried "wipe all" in shell, but it reported several errors with message "Read-only file system" and one "Permission denied".
I've also tried "wipe data", and got "permission denied" on opening /data.