As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING HEAVY MAINTENANCE, DURING EMERGENCY LIGHT TEST FAILED BAT/EPSU (11WL) ON PASSENGER CABIN. R & R BATTERY OF THE (EPSU) 11 WL ON PASSENGER CABIN IAW AMM 33-51-38-00-002-A AND 33-51-28-400-002-A AND PERFORMED OPS TEST (EPSU) IAW AMM 33-51-00-710-001-A. TEST IS OK