As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE WORKING WC #3351-2991 BATTERY AT LOCATION 15 WL FAILED. REINSTALLED OLD BATTERY SN # 877739 AND FWD TO MONITOR TO REPLACE BATTERY AT LOCATION 15WL. A/C OK FOR SVC. R/R EPSU BATTERY IAW A321 AMM 33-51. PASSED BITE TEST. OPS CHK NML. (LP# 8376388)