These units use what is called a switch mode supply. Can I assume that you have the 5V standby voltage around? If not, then there are further problems. Anyway... Can you post a picture of the power supply board? It will be easier to direct you on what to check if I can reference a picture. I suspect that what I call the kick-starter capacitor has failed. This is usually a 2.2ufd capacitor in the 50V range that starts the oscillations of the switch mode supply.
With a picture I should be able to direct you to the part.
Dan