As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GOUND POWER DROPPED OFFLINE WHEN SWITCHED TO APU GEN ,THE NR 2 FMC DID NOT COME BACK ON. ACFT GROUNDED. FOUND THE NR 2 FMC CDU BLANKED OUT . CYCLED AND RESET NR 2 FMC CDU CIRCUIT BREAKER, NR 2 FMC CDU POWERS BACK NORMALLY. ATTRIBUTE CAUSE TO TRANSFER OF POWER IAW AMM 34-61-01-400-802.