As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: WHILE PERFORMING EMERGENCY LIGHT SYSTEM TEST ON FLIGHT ATTENDANTS PANEL, FOUND MESSAGE EMERGENCY POWER SUPPLY UNIT BATTERY EMERGENCY LEFT. CLEANED EMERGENCY POWER SUPPLY UNIT 11WL CONNECTOR AND ACCOMPLISHED A SATISFACTORY BITE TEST PER AMM 33-51-00.