The LC4500 driver board status LEDs can be helpful for diagnosing improperly functioning systems.  In a properly functioning system the status LEDs should indicate:

D4 : blinking green
D8 : steady green
D16 : blinking green

D8 : Power status

If D8 is off then the 12V supply on the driver board is not present.  Check the supply and confirm it is present at the input of the board--if so then there is a hardware fault on the driver board.

If both the red and green portions of D8 are illuminated then either the MSP430 is not functioning properly or there is a hardware fault in the internal power supplies on the driver board.  Check instructions for status LED D16 to confirm if the MSP430 is functioning properly.

D16 : MSP430 status

If D16 is off or red (and D8 is solid green) then the MSP430 is not functioning properly or it has detected a hardware fault.  Go to the GUI's Hardware Access tab and try reprogramming the MSP430 with the MSP430 Firmware Upgrade controls, using the default firmware in the Firmware folder of the installed GUI.  If this does not restore system functionality and cause D16 to blink green then there is a hardware fault on the driver board.

D4 : DLPC350 status

If D4 is off then the DLPC350 DMD controller is not functioning properly.  Usually this occurs when incorrect data is programmed into the DLPC350 by the user or there is a power interruption during programming.  

Try reprogramming the DLPC350 with the Keynote default firmware located in the Firmware folder of the installed GUI.  If this restores the system functionality and causes D4 to blink green, then try again to program the DLPC350 with user-generated firmware.  

If reprogramming with Keynote default firmware does not restore system functionality then try reprogramming in boot hold mode.  Remove power to the driver board and slide DIP switch SW1 to the ON position.  (SW1 is on the right side just inboard of the small pushbutton switch.) With SW1 in the ON position apply power to the driver board and try to reprogram the DLPC350 with the Keynote default firmware.  When programming is complete, remove power to the driver board, return SW1 to the normal OFF position, and reapply power to the driver board.  If this does not restore system functionality and cause D4 to blink green then there may be a hardware fault on the driver board.