As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: DURING SYSTEM TEST AFT LEFT EMERGENCY POWER SUPPLY UNIT FAIL MESSAGE DISPLAYED ON THE CIDS. MAINTENANCE REPLACED THE AFT LEFT EMERGENCY POWER SUPPLY UNIT (AALA202309056800) AND BATTERY (AALA202309052578) PER AMM 33-51-38. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED.