Rd ii sr shut down problem

I have a RD II SR refer used to have codes 74 77 & 61 will start and turn off so I check contacts all ok check diesel in to fuel filter all ok check oil and water all ok removed circuit board cleaned all contacts with contact cleaner because I have seen some light mildew on the circuit board removed & reinstalled back now control panel in cab will not light up if I turn on black switch on position it will turn on and off buy itself so don’t know what to check any more please help.
:rolleyes:
Thank you