As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: DURING EPSU TEST GOT CLASS 1 FAULT FOR EPSU 12WL. MAINTENANCE REPLACED AND PERFORMED GOOD OPS TEST OF 12WL BATTERY OF THE EMERGENCY POWER SUPPLY UNIT (EPSU) IAW AMM 33-51-36-000/400-002-A AMM 33-51-00-820-801-AMM 33-51-00-710-001-A, AMM 23-73-00-740-012-A.