As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, NOSE GEAR WOULD NOT RETRACT AND RED UNSAFE LIGHT REMAINED ILLUMINATED. FOLLOWED COCKPIT OPERATING MANUAL PROCEDURE AND RECYCLED GEAR. UNSAFE LIGHT REMAINED ILLUMINATED. FLIGHT RETURNED TO DTW AND LANDED WITHOUT INCIDENT. MAINTENANCE SERVICE GEAR PER MM 32-21-2. GEAR OPERATION WAS CHECKED SEVERAL TIMES. OPERATIONAL CHECK OK.