As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS SIGNIFICANT SYSTEM, AFTER FMC INITIALIZATION AT GATE. LEFT FMC BLANKED THEN DISPLAYED "FMC L OUTPUT LOSS". REPLACED RIGHT FMC, LOADED NEW SOFTWARE FROM BINDER AND CROSSLOADED TO LEFT FMC MONITORED FOR MSG. NO MSG DISPLAYED AMM 34-61-01. PERFORMED FMC OPS TEST PER AMM 34-61-00. "PER HAL ENGINEERING RIGHT FMC REPLACED".