As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE LEVEL AT 17,000 FEET, THE AUTOPILOT BEGAN TO PITCH UP AND DOWN, THEN THE NOSE ABRUPTLY PITCHED DOWN AND THERE WAS A "TRIM FAIL" MESSAGE. (FLT 5457) REPLACED AUTO PILOT CONTROL PANEL. OPS CHECK GOOD AT THIS TIME. P/N: 622-6684-006 S/N ON: 440 S/N OFF: 1519