Overheating

I was charging my battery with the stock cable when the notification light starting flashing red and green. I took a look at the HTC Battery widget and it registered a temp of 59 degrees celsius (how ever hot that is) and the Health status said "Overheated". So I took it apart and let it cool off. The power immediately dropped from 100% to 75%.

I have no case on it, and haven't modded it in any way.

I went to a Corporate Sprint store and had the tech look at it. Which took an hour and a half. Said he couldn't replicate the issue and sent me on my way. Should I go back and demand a new battery?

EDIT: It JUST overheated AGAIN.

I had this issue the day before this happened. http://www.evo4gforum.net/troubleshooting-htc-evo-4g/battery-icon-can't-find-meaning/

On a side note, it really irks me you can't speak with the tech directly. You have to go through a sales rep. Information gets lost between the two...

Edit: I started a new thread because this one isn't specifically about the battery.

My new phone is working better. It gets a little warm but not as bad as it used to be with the other one so I'm happy. Sorry about peeps who are still having problems. I hope you get your phone working well soon.

By the way, today is the first day AFTER my 30 days so there's no going back now!!

If you've tried removing the battery for 30 seconds and it still doesn't help, take it to a store.

Mine started overheating when the battery got older.  I have had the phone for a year now and it started having the problem overheating around the 7 month mark.  I'm going to try a different battery and see if that fixes the problem.