The phone is full stock, no root nor any modifications were made, 4.1.2.
At the beginning of my adventure with this phone I experienced a problem with Media process eating the battery. That was probably caused by one of videos, faulty mp3 file or Gallery system application. Once or twice a day 46% of battery was eaten as shown in battery stats. However from time to time the phone just died and battery stats had just a blank space from the last reading The phone got hot because of CPU usage. As it also happened at night and affected an alarm clock and had to be dealt with.
I turned off Gallery, Media and Media history services (in App properities) and replaced them with independent applications. First problem was solved and the second one become clearly visible.
It looks like this:
There is nothing indicating extensive battery use:
The battery reading goes from 80% to 0% in 80 seconds and the phone dies. Nothing overheats, nothing hangs. After 1 - 2 days if 60% is shown and I restart it, it goes to 0% instantly.
It's either faulty battery or software bug :/
Any ideas what can I do with it apart from buying a new battery?