Start with the power supply and verify correct voltages there. Then move along the power chain for the controlled lamps until you end up at the MPU. Make sure to check fuses with a multimeter and not just your eyes. Also check to see if there is any alkaline damage from leaking batteries on your MPU.

I would still suspect the 8amp fuse first if you have no power at the lamp socket. Upstream from that is the bridge rectifier. Pop in a new fuse and see if the lamps return.