As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: DURING EMERGENCY POWER SUPPLY UNIT SYSTEM TEST EMERGENCY POWER SUPPLY UNIT 13WL AFT LEFT FAILED. REPLACED EMERGENCY POWER SUPPLY UNIT 13WL PER AMM 33-51-38-400-001-A AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.