As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN EMERGENCY LIGHTING BATTERY CAPACITY OPERATIONAL CHECK {A3NB-33-3-6013} - EPSU FWD LH MESSAGE FAILURE DISPLAYED ON TEST. REMOVED AND REPLACED FWD EMERGENCY POWER SUPPLY UNIT AS PER AMM 33-51-38/401. OPERATIONAL TEST GOOD.PARTS USED: 31-3350-9-9001, QTY :1 ROTABLE PARTS CHANGE WAS INDICATED - TT # 1749360 SN OFF 8571, POWER SUPPLY, P OFF 31-3350-9-9001 8571 ON 31-3350-9-9001 4341