As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AN OVERNIGHT LINE CHECK THE EMERGENCY EXIT SIGNS AT DOORS ONE LEFT AND FOUR LEFT WOULD NOT ILLUMINATE. MAINTENANCE FOUND POWER SUPPLY AND BATTERY PACK M731 TO BE DEFECTIVE AND REPLACED IT. SYSTEM OPERATION WAS NORMAL AFTER THE POWER SUPPLY AND BATTERY PACK WERE REPLACED.