My S3 mini been running stock android 4.1.2 for over a year now with no issues. Yesterday the phone just reboots by itself and the battery went from 60% to 14% in a second. Then the phone got stuck in a reboot loop, I had to take out the battery to make it stop rebooting every second. I tried charging the phone all night, for 8 hours, got 10 minutes of usage out of it before it started rebooting again and the battery inexplicably jumped from 90% to 14% ! The phone is only usable when plugged to the AC, basically not a mobile phone anymore.
Did a factory reset, Thought it might help, it didn't. The phone works fine when plugged to the AC, it only starts rebooting a few minutes after I unplug it.
Help please, should I get a new battery?