As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF AUTOPILOT TRIM PITCHED UP. PILOT RETURNED TO AIRPORT AND HAD SAFE LANDING. FOUND TRIM SWITCH IN PILOTS YOLK SHORTED OUT. FOUND TWO WIRES TOUCHING, CAUSING PITCH UP. RESOLDERED CONNECTOR AND INSULATED FROM OTHER TERMINALS.