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 PERIODIC SERVICE CHECK, FOUND EMERGENCY POWER SUPPLY UNIT BATTERY 14WL FAULTED DURING BITE CHECK. MAINTENANCE REPLACED EMERGENCY POWER SUPPLY UNIT BATTERY 14WL IAW AMM 33-51-38. BITE CHECK GOOD. OPS CHKD GOOD.