In case anyone else with an Android phone is having problems with overheating and battery drain, I found the solution. It’s a bug in Media Server that afflicts some ROMs. When too many files build up on your phone, it goes bonkers. Here’s the fix:
1. Remove all unneeded files from your phone (photos, music, videos, and any other files you have in volume – e.g. I had several hundred crossword files). I moved what I wanted to save but didn’t need on my phone to my computer, and deleted the rest.
2. Go to Settings->Apps->All, scroll down to find “Media Storage”, click Force Stop, and then Clear Data. In the screenshot, Media Server has only 7.31MB of data. Before I cleared it and rebooted, it was over 52MB. How big is yours?
3. Restart your phone.
This will force Media Server to start again clean and reindex everything, restoring your phone to its original cool-running, long-battery-life state.