My Nexus 7 wouldn't boot , no matter what combination buttons I pushed.. (it was fully charged when this happened.) After letting it set for 2 weeks out of frustration, I opened it with one of your handy dandy plastic opening tools, unplugged the battery for about 2 minutes, reattached the battery and closed the device back up. I then pushed the power button as normal, and it BOOTED UP... been using it since. Opening the device up is very easy and this is definately worth a try... My theory, is that the Nexus never would really turn off, so unplugging allowed the OS to reset.... maybe ? anyway, it worked...