Zune dead, what did I do?

Okay, so the other day i was syncing music, and i unplugged my zune, and it flashed to play mode and then shut off. It would not boot, and wouldn't respond to being plugged in to either my laptop or the wall outlet.

I left it plugged in to the wall overnight, and it turned on, and was fully charged when i woke up. then it died in a day (it usually lasts about 3 days with how i use it), and now it won't turn on again.

Did i fuck it up somehow? What can I do to fix it?