As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AS SOON AS THE AVIONICS MASTER WAS TURNED ON THE AP BEGAN SELF-TEST, AND IT COULD NOT BE INTERRUPTED. MX CYCLED CIRCUIT BREAKERS AND POWER WITH SAME RESULT. REMOVED AND REPLACED APMS2360; TEST FLIGHT SUCCESSFULLY COMPLETED; NO FAULTS NOTED.