Wwhats the h/w issue?

recieve the computer with customer claiming mobo dead (according to geeksquad) saved them 250 doin it myself. press power button and nothing happens. fans dont move no new lights appear, double checked all power cables. opened the psu, saw some gunk on one of the capasitors and some more on a copper coil thingy. mobo light is green indicating its good, [psu doesn’t have a light indecator ](unlike the last board, but still got the same symptoms). Im thinking that the power button on the front panel is somehow bad or the psu is bad somehow like as in not pushing enough power.