¿Has probado con un hard reset?
How to hard reset:
Warning! All data will be lost!
1.Power off your phone
2.Press together volume down + power key
3.Press power key to erase all data
4.Press power to confirm
5.Wait until the phone restarts
That's it!
- See more at:
http://factory-reset.blogspot.com.es....NiRCNjHh.dpuf