As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPT AUTOPILOT DISENGAGE BUTTON WILL NOT DISENGAGE AUTOPILOT ON CONTROL WHEEL. GROUNDED - YES. FAULT CODE 221 550 31, INITIAL INSPECTION FOUND CONTROL WHEEL SWITCH DIRTY, CLEANED SWITCH COLLAR. PERFORMED B737-800 FIM 21-13 TASK 809, EVALUATED SYSTEM REF FIM 21-11 TASK 801, NO DEFECTS NOTED. LAND VERIFY TEST PER B737-800 AMM 22-11-00-740-806 NO DEFECTS NOTED. AIRCRAFT AUTOLAND QUALIFIED.