As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3424 THE CREW REPORTED AFTER POWERING DOWN AIRCRAFT IN CORRECT SEQUENCE THE AFT PORTION OF THE CABIN EMERGENCY LIGHTS REMAINED ON AND EXTERIOR LIGHTS REMAINED ON. THE AIRCRAFT WAS REMOVED FROM SERVICE. TROUBLESHOT REMOVED AND REPLACED BATTERY PACK AND BATTERY POWER SUPPLY. THE OPERATIONAL CHECK WAS GOOD IAW EMB MM 33-50-04. THE AIRCRAFT WAS RETURNED TO SERVICE.