I found this gem today when I contacted Lexmark Tech. Support.

If you have the machine listed above (tested on an E462dn) and it main symptom is it's totally dead, try this before ordering a LVPS/HVPS or Controller Board.

1. Remove the right cover exposing the controller board.
2. WITH THE POWER OFF! Disconnect the Paper Feed Clutch (J26) from the board.
3. Try powering the machine up. If it comes alive, replace the paper feed clutch (40x5370 for the E462) before replacing any expensive (!) parts.

Lexmark informed me that this does happen but the occurrence is "rare"(?).