As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: DURING EMERGENCY POWER SUPPLY UNIT SYSTEM CHECK FAULT MESSAGE FOR BATTERY / EMERGENCY POWER SUPPLY UNIT 12WL. MAINTENANCE ACCOMPLISHED TSM 33-51-00 AND CLEANED EMERGENCY POWER SUPPLY UNIT 12WL CONNECTOR. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO FAULTS NOTED.