As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AIRCRAFT NOT GROUNDED) DURING EPSU SYSTEM TEST BAT/EPSU(12WL) EMER RT FAULT. FOLLOWING TSM 33-51-00-810-856-A, REMOVED AND REPLACED BATTERY FOR EPSU 12WL IAW AMM 33-51-38-000-002-A AND AMM 33-51-38-400-002-A. OPS CHECKS SATISFACTORY."