As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AIRCRAFT NOT GROUNDED) EMERG LIGHT TEST FAILS EPSU BATTERY MID L / REMOVED AND REPLACED BATTS AT L MID (11WL) AND AFT L (13WL) AND BOTH POSITIONS BITE CK GOOD. SEE LOG PAGE 1897000 FOR FURTHER TROUBLESHOOTING REF AMM 33-51-38-000/400-002-A."