(I already tried with another Power Button) I must short and hold for 2-3 secondes the Green (PS_ON) and the Black (GND) cable at the ATX connector to start up my Mobo. I made a video to show ...

BR><BR>I then plug it all back in and notice that an LED on the motherboard is actually on ... it's closed when I depress the power button. So the power switch is functioning correctly.< ...