As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN SWITCHING FROM GROUND POWER TO APU POWER, THE RIGHT SOURCE OFF LIGHT ILLUMINATED. ACFT GROUNDED. PERFORMED A POWER SWITCH FROM GROUND POWER TO APU POWER SEVERAL TIMES WITH NO DEFAULTS NOTED. GOOD FOR RETURN TO SERVICE AT THIS TIME.