Dude sorry if this answer makes you feel stupid, but make sure the wire is plugged in!
Also try a different outlet, do the basic free fixes first.
Open the thing up, check if the fans spin up or anything.
Also look at the fans see if they spin at all, sometimes when you hit the power, check if the fan even moves at all.
It doesn't have to spin, just if it moves at all.
Also is there a light on the motherboard?