As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ROTATION AT 4000 FEET PILOTS LOST BOTH FMC"S AND LATERAL AND VERTICLE NAV. AFTER MULTIPLE ATTEMPTS THEY WERE RESET. THEN A REPEAT ELEVATOR FEEL DIFFERENTIAL LIGHT CAME ON WITH A MUSHY FEEL. THIS LEAD TO AN AIR TURN BACK WITH AN EMER LANDING DECLARED FOR OVERWEIGHT., OVERWEIGHT CONDITION REPORTED WITHIN PARAMETERS. MAINTENANCE REPLACED THE ELEVATOR FEEL COMPUTER. THE AIRCRAFT WAS GROUNDED.