XPS 730x motherboard troubleshooting

I think the motherboard died. I am trying to find out for sure before spending time and money tracking down a motherboard, installing and finding out it is not the issue.

Is there info anywhere on the LEDs on the motherboard and master control board?

Like LED 18 (maybe 16, hard to read) on the mobo is amber when the computer is plugged in and not turned on. Is that an error indicator or something else? It turns off when I try to turn the computer on and LED 17, next to it, turns green. Other LEDs turn on blue next to the vido and sound cards when I hit the power button. The power button turns solid blue and stays on. The little harddrive light in the front turns blue initially then turns off. etc.

But the computer never POSTs. No error beeps or anything. Nothing shows on the screen. Just the fans come on 100% as usual, then they slow down except 1 fan but I can't tell which one it is.I have not been able to find any real technical data on the motherboard. The so called service manual on the dell site for the xps730x does not get into anything beyond the basics.