As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#373, BOS-AUA. '(AIRCRAFT PERFORMED AN AIR TURN BACK TO BOS) ' MCDU 1 BLANK ON CLIMBOUT AT FL 200. THE COMPUTER RESET PROCEDURE WOULD NOT FIX MCDU1; REMOVED AND REPLACED CAPT'S MCDU PER AMM 22-82-12. OPERATIONAL TEST OF MCDU SATISFACTORY.'