As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON GROUND AT PAKT FMC DISAGREE LIGHT MOMENTARILY ILLUMINATED AND THEN EXTINGUISHED. QRH CHECKLIST REFERENCED ALSO- GROUND POWER UNIT AT PAKT FAILED/DROPPED OFFLINE LEFT A/C ELECTRICALLY UNPOWERED AND OPERATING ON BATTERY POWER FOR SEVERAL MINUTES. GROUNDED - YES. ACCOMPLISHED FMC SENSOR TEST ON BOTH FMC'S, BOTH SHOW OK REF B737-800 AMM 34-61-00-026.