As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: SEVERAL EMERGENCY LIGHTS NOT COMING ON IN AFT CABIN ON CEILING AND SEATS. MAINTENANCE ACCOMPLISHED A BITE TEST AND FOUND EMERGENCY POWER SUPPLY UNIT 13WL FAILED THE SYSTEM TEST. EMERGENCY POWER SUPPLY UNIT 13WL WAS REPLACED PER AMM 33-51-38 AND A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED.