Out of nowhere, printer will not power up. Only indication that it is getting power is the small green LED on the actual power supply "cartridge" is on. So I open it up to test the voltage, and notice a very faint clicking sound when the supply is plugged in. I test for voltage at various points and the last point in which I get 30 volts is the plug that plugs into the circuit board. So I have correct voltage going into the board, but nothing coming out anywhere, and a faint repetitive clicking sound.
Any clues, hints suggestions? I even tried jumpering the contacts of the power switch with no luck. Once it hits that board, I'm lost! The only contact between the board and the switch is a thin ribbon that plugs in to the board, but I can't measure the female "plug" to see if it is getting power.

Possibilities are unlimited. You probably need to get the unit serviced. Lexmark does not provide component level diagnostics or repair parts. It is FRU (Field Replace Units) only.

There could be a direct ground short from the motherboard.

If you are getting 30 VDC out of the power supply then that is working. You can verify by reading the label on the power supply transformer. It will tell you what the output voltage and amperage should be.

You could also have a jammed carrier. This happens when the carrier is driven beyond either of the head stops.