As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. CABIN EMERGENCY EXIT LIGHTS CAME ON DURING FLIGHT, UNABLE TO RESET FROM CABIN INTERCOMMUNICATION DATA SYSTEM PANEL. UNABLE TO TURN OFF USING FLIGHT DECK SWITCH. FOUND 2EA EMERGENCY POWER SUPPLY UNIT BATTERY LOW VOLTAGE. REPLACED BATTERIES AT 10WL (AALA202101299009) AND 15WL POSITIONS, AS PER AMM 33-51-38.