Hello,
I can give you some advices:
1) simple unplug it for 10-15miniutes and then plug it back in
2) the problem may comes from power unit faulty -> try to power it in another power supply
3) check standby volts on power board, but if you got no red(if it have red..) standby led on front of tv then it can be bad power board or main board.?
4) the TV may need a service...