As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: EMERGENCY POWER SUPPLY UNIT COMMUNICATION FAULT MESSAGE DURING SYSTEM TEST. MAINTENANCE REPLACED THE BATTERIES FOR THE FORWARD EMERGENCY POWER SUPPLY UNIT (AALA202309053439) AND THE LEFT MID EMERGENCY POWER SUPPLY UNIT (AALA202309058255) PER AMM 33-51-00.