As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - EEL - DURING 4-DAY CHECK THE LT OVERWING EMERGENCY BATTERY PACK AT EMERGENCY POWER SUPPLY UNIT (11WL) FAILS PUSH BUTTON TEST. MAINTENANCE REMOVED AND REPLACED LT OVERWING EMERGENCY POWER SUPPLY UNIT (11WL), OPERATIONAL CHECK WAS GOOD.