What was found
ON PREFLIGHT EMER LIGHTS WERE ARMED AND FAILED TO ILLUMINATE. PER MCC PROCEDURE, THE APU WAS STARTED AND GIVEN 30MIN TO CHARGE. THEN, THE AIRCRAFT POWERED DOWN AND EMER LIGHT FAILED TO ILLUMINATE AGAIN. REMOVED AND REPLACED EMERGENCY BATTERY PACKS 1,2,3 AND 4. OPS CHECKS OF BATTERIES AND EMERGENCY LIGHTING GOOD AT THIS TIME. TOOK PHOTOS AS RECORD. NO OTHER DEFECTS NOTED. REF. CE680A MM 33-50-06.