Try to use combination key to do soft reset/hard reset and do it for few times.Just wait for 30 minutes to 1 hour after every hard reset/ soft reset. I had the same problem when restore to factory setting and luckily this combination key saved my day. I did this for like 3 times before my phone reboot to normal.
Soft reset>Hold volume down button +lock button(hold for 10-15 second until it vibrate) = just like normal restart
Hard reset >Hold volume down button +lock button +camera button(hold for 10-15 second until it vibrate) = restore to factory setting
