As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER RECONNECTION & OPERATIONAL TEST OF EMER BATTERY, BATTERY PACK 4 IN CABIN BETWEEN FS 849.00 & 865.00 IS INOPERATIVE. BATTERY FOUND TO BE DEAD. RECEIVED SERVICEABLE BATTERY PACK POSITION 4 FROM ACFT N903XJ. INSTALLED SERVICEABLE EMER BATTERY PACK AT POSITION 4 IAW AMM 33-51-17-000-802-A02 & 33-51-17-400-801-A02. OPERATIONS TESTED GOOD IAW 33-51-17-710-801-A02.