As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AIRCRAFT GROUNDED) NRC 7000-0009: DURING OPERATIONAL TEST OF EMERGENCY POWER SUPPLY UNIT (EPSU), EPSU 11WL (EMER L) AND 13WL (AFT L) INDICATE BATTERY FAULT / EMERGENCY POWER SUPPLY UNIT (EPSU) , EPSU 11 WL (EMER L) AND 13WL (A.JH' L) BATTERY REPLACED AND TESTED SERVICEABLE IAW AMM 33-51-38-000/400-00I-A.