I held the power button down for 10, 20, 30, up to 90 seconds. It won't do anything. I've held down the power, home, and volume rocker buttons down for equal amounts of time, with the same results (Nothing happens). When I plug it in to the charger, no lights come on, the battery image doesn't come on, etc. The ONLY response I can get is when I plug it into my computer and press the power button, the computer makes the "a-ha" noise like it recognizes something, but that's as far as it goes. I go into devices, and the phone isn't recognized.
Going to a Sprint store today when they open, hopefully they can figure out what's wrong and/or give me a replacement. I can't understand how the phone would just go off and do this when I haven't done anything to it to cause it (never tried to flash roms or root or anything. 100% stock).