As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING MAINTENANCE WHILE THE CLEANERS WERE ON THE AIRCRAFT OVERNIGHT THE EMERGENCY LIGHTS AT THE EMERGENCY EXIT DOORS OVERWING CAME ON. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE BATTERY PACK ON BATTERY POWER SUPPLY NR 3 THE OPERATIONAL CHECK WAS GOOD IAW EMB 145 AMM 33-50-04 AND 33-50-00. THE AIRCRAFT WAS RETURNED TO SERVICE.