What was found
REAR AND LAV EMER EXIT SIGN NOT ILLUMINATED. RESERCHED CE-680 WIRE DIAGRAM BUT SHOWED LIMITED INFORMATION. CONTACTED MCC AND ASKED FOR ADDITIONAL WIRE: REFRENCES THAT WE DO NOT HAVE ACCESS TO. RECIVED REFRENCES AND DETERMINTED DISCREPANCY LEAD TO #4 EMERGENCY BATTERY. REMOVED LAV CLOSET ITEMS AND REMOVED ACCESS PANELS AS REQUIRED. REMOVED CANNON PLUG AND CHECKED FOR POWER OUT OF BATTERY. FOUND 0VDC. WHILE RECONNECTING CANNON PLUG NOTICED FUSE WAS LOOSE AND NOT INSTALLED CORRECTLY. REMOVED AND REINSTALLED #4 EMERGENCY BATTERY FUSE AS REQUIRED. TURNED ON EMERGENCY LIGHTS AND ALL LIGHTS ILLUMINATED. OPS CHECKS GOOD. STARTED APU AND RECHARGED EMGERGENCY LIGHTS FOR 1 HOUR. SHUT DOWN AIRCRAFT AND CPS CHECKED EMEGERGENCY LIGHTING. OPS CHECKS GOOD, RE-INSTALLED LAV CLOSET ACCESS PANELS AND LAV CLOSET ITEMS. REF CE-680 AMM 33-50-10 AND CE-680 WDM 33-50-01