As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STARTED APU ON GROUND TAXI IN. TRIED TO SWITCH ELECTRICAL AND THE APU WOULD NOT ACCEPT THE LOAD. WITH GROUND POWER PLUGGED IN, WOULD NOT ACCEPT IT UNTIL NR 1 ENG GEN SELECTED OFF. THEN GROUND POWER WORKED. ACFT GROUNDED. REPLACED NR 1 GENERATOR CONTROL CIRCUIT BREAKER, C801. OPS CHECKED GOOD IAW AMM 24-21-41.