Blow it! just received a second hand PS4 and had a similar issue - when we connected the power the light flashed blue, there was a faint click from inside, then the light went off. Nothing came on the tv. Inspired by the posts above I blew into the ports at the back and got a face full of dust. Blew until no more came out. Plugged it in again and suddenly it works perfectly! a big cloud of dust came out as the fan came on when it finally powered up properly.