I have a Samsung galaxy grand prime plus, the problem is it keeps on showing “not registered to network” and I can not perform hard reset using Power + Volume up/down as it does not get to the reboot mode instead it restarts like a phone that was off. Also I tried manual reset via settings and still this does not help as it is not responding to this command. What can I do to do factory/original settings on my phone please help me. I am in South Africa and