As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
REFERENCE LP 294881. AIRCRAFT WAS IN FOR SERVICE CHECK. FOUND (14WL) ESPU BATTERY INOP DURING OPERATIONAL TEST OF EMERGENCY LIGHTS. REMOVED AND REPLACED EPSU BATTERY (14WL). PERFORMED OPS CHECK OF THE EMERGENCY LIGHTS. OPS CHECKS GOOD. A/C OK TO CONTINUE . IN REF TO AMM 33-51-38-000-002-A/END/