I’ve recently been having problems with my Nexus 7 not booting up after it completely runs out of battery. Specifically – even if I have charged it overnight, if the power is off and I click the power button, then it does not turn on!
I’m not sure if this is related to 4.2.1, but this problem didn’t seem to occur with 4.1.1. I’ve got the 8GB version of the Nexus 7.
To solve it, press and held on to the power button until it starts up (for approximately 30 seconds.)
Note that Asus has a support page which mentions this titled Nexus 7 won’t start up. I agree with their recommendations, but I’d add that you’ll probably need to press and hold it for longer than what they recommend (around 30 seconds vs their recommended 15).
Update: after a quick search, a thread on Android Enthusiasts titled Nexus 7 wont boot after complete discharge corroborates my findings.