As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING HEAVY MAINTENANCE, EMERGENCY LIGHT TEST WAS PERFORMED, REAR EXIT SIGNS DID NOT ILLUMINATE. OPS TEST WAS PERFORMED RESULTING IN BATTERY FAULT ON EPSU 13WL. REMOVAL OF THE BATTERY WAS PERFORMED IAW AMM TASK 33-51-38-000-002-A. OPS TEST PERFORMED IAW AMM 33-51-00-710-004-A.