As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DUAL FMC FAILURE AT FL350. SELF RESTORED AFTER 2 MINUTES. GROUNDED - YES. NOTED "PMG FAULT" ON BOTH LEFT AND RIGHT FMC COMPUTERS, DEU 1 AND DEU 2 BOTH NOTED FAULTS 31-64770 AND 31-67400 AS WELL. REMOVED AND REPLACED FMC #1. SOFTWARE LOADED AND OPS CHECKED GOOD REF B737-900 AMM 34-61-02. REMOVED AND REPLACED FMC #2, CROSSLOADED SOFTWARE AND OPS CHECKED GOOD REF AMM 34-61-01. PERFORMED POST INSTALLATION TEST OF #1 FMC AND #2 FMC, TESTED PASSED, REF AMM 34-61-02.