As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
REFERENCE NR 5001330695-0010. AIRCRAFT WAS NOT GROUNDED AND IS IN CHECK FOR SCHEDULED MX. DURING EPSU BATTERIES CAPACITY TEST, EPSU BATTERY (13WL) FAILED. REPLACEMENT IS REQUIRED IAW AMM 33-51-38-000-002-A REV.98. REPLACED EPSU BATTERY (13WL) IAW AMM 33-51-38-400-002-A REV.98 P/N OFF: 3214-31, S/N OFF: 929867 / P/N ON: 3214-31, S/N ON: 954040 B/N: 7583. MX ACTION IS ACCEPTABLE.