Went to bed at 11pm, working fine but relatively low battery (45%). Woke up at 5am, completely dead. Plugged into charger, nothing, no lights, no charging.
I would recommend that you start with forcing the phone to shut down and see if you then are able to charge and/or power it on again. To do that, press and hold the power button and volume up buttons at the same time for roughly 10 seconds (you will get a few vibrations).
If you still can't power it on and there is no indication that the phone is charging, try charging it for 3-4 hours using a wall socket and the original charger and cable that was included together with your phone.
