If you’ve got a Nexus7 and one day discover that it will not turn on, refuses to charge and also emits a strange static burst of noise. Well you my friend have found what some people discovered is the Nexus7’s battery protection phase.
The battery protection phase seems to stop the device from charging to reduce the likelihood of further damage to the battery (since it ran down to almost 0%)
To get your Android back to work, do the following steps:
1. Plug Nexus 7 to a wall charger (or PC)
2. Immediately press Volume Down and Power at the same time to reach the bootloader
3. From bootloader menu, press Volume Down until you see “Power Off Device.”
4. Press the Power button to select the ‘Power off device’ option
5. Once your device is off, unplug the charger and then plug it back into the device.
That should be all that you need, just let the device charge and you should be back in action.
If that didn’t fix it for you, pop open the case of the Nexus7 (it is on little teeth that pop open if you get your fingernail in between the cover and the bezel). Once the cover is off, you will see a big black battery with a single (multi color wire) connector, if you unplug the battery and plug it in again, I’ve seen reports of this being the fix for people. Not sure if it is oxidization or loose connection on the battery.
Hope one of these helps you get going again with your Nexus 7.