Hi,
Unless the power cord looks old and tired, it is more likely that the problem is on the printer circuit board.
Here’s the ifixit [guide|22547] guide that may help in finding the problem.
If you decide to open the printer but can’t see anything obviously wrong with the circuit board after following the repair guide, post some close up images of ''both sides'' of the board back here. Here’s how to do this on ifixit. [guide|21499]