As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GNDED. EMER POWER SUPPLY UNIT FAILED TEST ON WEEKLY CHECK. REPLACED LT POWER SUPPLY UNIT IAW AMM 33-50-00. INSPECTED THE POWER SUPPLY WITH SHOP BATTERY, NO DEFECTS WERE NOTED WITH A FULLY CHARGED BATTERY. THE POWER SUPPLY WAS RETURNED AS SERVICEABLE.