Faulty power button?

I have a PC that will not turn on. The motherboard shows it is getting power (via LED light) but when I click the power button nothing happens, no fans start up, no posting or anything. I have replaced the PSU still nothing. I unplugged and removed all unnecessary components and still get nothing.

the only thing I can think of is a bad power button, is this plausible? Or does anyone have anything else I could try.