As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OPERATIONAL CHECK OF CABIN EMERGENCY LIGHTS {A3NB-33-3-6012} - FAULT 'EPSU INT LOAD AFT L' SHOWING. TEST AT LEFT AFT EPSU GETS NO RESPONSE. REPLACED POWER SUPPLY ASSEMBLY REF. AMM 33-51-00. OPS CHECKS GOOD.PARTS USED: 31-3350-9-9001,QTY :1 ROTABLE PARTS CHANGE WAS INDICATED - TT # 1523432 SN OFF 8437 POWER SUPPLY, P OFF 31-3350-9-9001 8437 ON 31-3350-9-9001 1069