As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: EMERGENCY POWER SUPPLY UNIT SYSTEM TEST HAS 4 FAULT MESSAGES. REPLACED THE BATTERIES ON EMERGENCY POWER SUPPLY UNITS 11WL (AALA202207271687), 12WL (AALA202207275364), 14WL (AALA202207275171) AND 15WL (AALA202207273289) PER AMM 33-51-38. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED