What was found
UPON TESTING THE EMER LIGHTS ON POWER UP, THE MAIN EXIT LIGHT OVER THE MAIN CABIN DOOR DID NOT ILLUMINATE. VERIFIED DISCREPANCY, ATTEMPTED TO CHARGE #1 BATTERY PACK WITH NO SUCCESS. ACCESSED #1 BATTERY PACK, INSPECTED THE FUSE ON THE #1 BATTERY PACK AND FOUND IT OPEN, REMOVED FUSE PN S2565-5, INSTALLED NEW CUSTOMER SUPPLIED FUSE PN S2565-5, OPERATIONAL CHECK IS GOOD, OPERATED LIGHTS FOR 10 MINUTES THEN CYCLED ON AND OFF SEVERAL TIMES WITH NO DEFECTS NOTED IAW AMM 33-50-10.