My Nexus 7's battery was very low and I charge it through a PC USB. I played reckless racing game and then putted it on the desk for awhile. The tablet actually made a "fizzle" sound, suddenly static-screened for 2 seconds and then died. I unplugged the USB and the device turnned black immediately and was overheatted.
Charging from a PC doesn't provide enough power and just makes it into a low battery. To fix the issues, wait 5 mins to let it cool, hold the power button for 30s to boot up, and then use the OEM charger. If it's still not working, taking it for a replacement.