As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2556 - MSP TO EWR - FLIGHT CREW DIVERTED FLIGHT TO MKE DUE TO LOUD NOISE ON NOSE AREA AFTER TAKEOFF. CREW LANDED ACFT UNEVENTFULLY. MX FOUND GPU DOOR OPENED. MX INSPECTED AREA AND FOUND NO DAMAGE. MX REMOVED AND REPLACED GPU DOOR AND PERFORMED OPERATIONAL CHECK SUCCESSFULLY. ACFT WAS APPROVED TO RETURN TO SERVICE.