HTPC project, part 2 - no good

Damn, the thing wouldn't even start after I put it together. Pressing the power button does exactly zilch. I checked the cabling at least five times, read the chassis and motherboard documentation I don't know how many times and everything seems ok. I even checked the power button with my multimeter - it works.

I had to take the thing to the shop since I don't have spare parts to try and replace parts to see which one is faulty. I believe it must be one of PSU, motherboard or chassis. PSU does give some power since the LCD on the chassis lights up and a LED is turned on on the motherboard. But maybe it doesn't give the +12V correctly? Or for some reason the PSU is not signalled to start pumping out power when the power button is pressed.

My main suspect is the motherboard, though. Lets see what they say in the shop. This delay is just annoying since I cant' start installing Ubuntu and XBMC.