Battery drain when phone is off, overheating

Recently my phone has been overheating. Even when turned off it will heat up and drain the battery. I've tried replacement batteries.

I've read many threads/articles about turning off wifi/4G/keep the screen low/etc... I've done factory resets and installed a caynogen ROM.

The phone had issues before - bluetooth/wifi stopped working, some trouble with the SD card.

I noticed that apparently it was water damaged at some point or at least the indicator says so. I'm guessing it's from steam in the bathroom as I'm certain I've never gotten truly wet.