As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: FLIGHT ATTENDANT REPORTS EMERGENCY LIGHTS CAME ON IN TAXI OUT THEN WENT OFF INFLIGHT, THE LIGHTS CAME BACK ON IN DESCENT AND STAYED ON. MAINTENANCE FOUND FAULT MESSAGE EPSU(16WL) OWD R AND REPLACED EMERGENCY POWER SUPPLY UNIT 16WL PER AMM 33-51-38. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO FAULTS NOTED.