As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER LEFT ENG START, LEFT FMC WENT FULL BRIGHT WHICH CAUSED AND OVERLAY OF LINES. AIRCRAFT BACK TO BLOCK AND GROUNDED BY MAINTENANCE. MAINTENANCE DEFERRED THE LEFT CDU IAW MEL 34-61-1-1A. MAINTENANCE PROCEDURES COMPLIED WITH. PLACARD INSTALLED. AIRCRAFT RETURNED TO SERVICE.