As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE - FLT 4294 THE CREW REPORTED AN AUTO TRIM FAIL MESSAGE WHEN AUTOPILOT WAS ENGAGED. THE AIRCRAFT RETURNED TO CLE AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE HORIZONTAL STAB CONTROL UNIT (HSCU). OPERATIONAL CHECKS WERE GOOD.