As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - EEL - NR 3984391 - DURING OVERNIGHT MAINTENANCE THE LT OVERWING (11WL) EMERGENCY LIGHT EPSU AND BATTERY FAILED. MAINTENANCE REMOVED AND REPLACED THE LT OVERWING EMERGENCY POWER SUPPLY UNIT AND BATTERY IAW AMERCIA WEST AIRLINES TASKCARD R1C33303. OPERATIONAL CHECKS WERE GOOD. BATTERY; MFG DIEHL; PN 3214-30