As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDING GEAR WOULD NOT RETRACT AFTER TAKEOFF. THE NOSE WHEEL STEERING WAS OPERATIONAL AND THE AIRCRAFT WOULD NOT PRESSURIZE. THE FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. FOUND SPRING ROD TO GROUND SHIFT MECHANISM HAD FAILED. REPLACED THE SPRING ROD. OPERATIONAL CHECK OK. AIRCRAFT RETURNED TO SERVICE.