its not a software problem
1,remove the Nexus battery
2,then press and hold 20 sec on power on button
3,then connect battery put (5v/105amp)charger
4,check after 5 hours
5,if same problem its continued
6,check usb dc socket (if any shake)
7,replaced USB port
8,after also the same problem its continued remove the battery and remove the battery black colour paper
9,when check battery pcb board check + and - put a dc (7 to 9 volt)voltage directly within 1 hours for battery boosting
10100% working
all the best!
searching for nexusservicecenter.com or , any great service focus will have the capacity
to handle the issue.