As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING HEAVY MAINTENANCE, EPSU BATTERY 12WL FAILED TEST; REF LHT NR 5000852972-0010 REMOVED EPSU WITH LOW VOLTAGE IAW AMM 33-51-38-000-001-A REV 76. INSTALLED NEW EPSU IAW AMM 33-51-38-400-001-A REV 76 OPS TEST OK IAW AMM 33-51-38-740-050-B REV 76