As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: DURING TAKEOFF ROLL, FIRST OFFICER LOST PITCH AND ROLL GUIDANCE. THEN ON CLIMB OUT, COULD NOT SELECT DIRECT TO A POINT IN LNAV, AND COULD NOT ENGAGE HEADING SELECT. ALSO, UNABLE TO SELECT AUTOPILOT-B AND AUTOPILOT-A WOULD ENGAGE ONLY IN RTE 2. AIRCRAFT AIR INTERRUPTED BACK TO AND LANDED SAFELY AT MIA. FOUND DFCS BITE TEST (FCC)-FLIGHT CONTROL COMPUTER-B FAILURE. REMOVED AND REPLACED FCC-B. PER PER AMM 22-11-33. OPERATIONAL CHECK NORMAL.