There are 3 LEDs. As Dok said, it sounds like you have lost the +5V. You are dead as a doornail until you get that fixed. It is normally a fairly easy fix.
Pull the PS board and check the header pins for burned pins or cracks in the solder joints (or just reflow them).
Check the voltages on the power supply board when it is plugged in and the output power cable is disconnected (if something is fried, no sense in taking chances with the game boards).
Voltages should be checked at the following places:
a) Test point 1 - the resistor leading to LED 1 (on the side away from the LED) = 5.1VDC
b) Test Point 5 - post marked TP5 = 12.8VDC (may be higher)
c) Test Point 6 - post marked TP6 = -14.8VDC (may be higher)
d) IC2 pin 6 = +7.3VDC
e) IC2 pin 5 = +5.1VDC
f) Pin 3 of connector to heat sink (green wire) = 12.8VDC (may be higher)
g) Pin 2 of connector to heat sink (white wire) = 6.7VDC
h) Pin 1 of connector to heat sink (yellow wire) = 5.3VDC
If any of those are off, you will need to do some trouble shooting and repair. Or send it to one of us that repairs power supply boards.
ken
Edit: You should also be getting 5.1VDC out of IC2 Pin 3 and Pin 4. If you are getting the right input voltages and the output voltage are off you may need to replace IC2.