As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: DURING CIDS OPERATIONAL TEST OF THE EMERGENCY POWER SUPPLY UNITS, FAULT MESSAGE FOR EMERGENCY POWER SUPPLY UNIT 13WL DISPLAYED. REPLACED EMERGENCY POWER SUPPLY UNIT 13WL (AALA202307110577) AND BATTERY (AALA202307115881) PER AMM 33-51-38. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED.