Ya you are right there fore just try a different socket .... coz the electric supply and the wireing is the issue i noticed

that's not a fault in phone actually some places have no good earthing try a different socket you will come to know that the problem is in the supply of electricity of the socket ... or else go to the showroom back ... May be the charger has some iss...

What is the problem actually ?

the patch is not installed properly missing some file go to a service centre and get it reinstalled . mostly will resolve the problem.