As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY POWER SUPPLY UNIT 12WL FAULT LIGHT. AIRCRAFT GROUNDED. REPLACED EMERGENCY POWER SUPPLY UNIT 12WL AND REPAIRED LIGHT CONNECTOR AT ROW 21R WHICH WAS SHORTED TO THE LUGGAGE BAR AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 33-51-38 PB 401.