As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FOUND EMERGENCY LIGHTS WILL NOT COME ON WITH EXTERNAL POWER, MAIN BATTERIES OFF. MAINTENANCE REMOVED AND REPLACED BATTERY PACK FOR POWER SUPPLY UNIT AT OVERHEAD BIN 1AB. OPERATIONAL CHECK WAS GOOD AND AIRCRAFT WAS RETURNED TO SERVICE. (M)