As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - CREW REPORTED MAIN LANDING GEAR DOOR WARNING INDICATION. GEAR WAS MANUALLY RELEASED. EMERGENCY DECLARED FLIGHT RETURNED DEN LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND RIGHT MAIN LANDING GEAR DOOR SENSOR TARGET BROKEN. REPLACED GEAR DOOR UP AND LOCKED TARGET. SYSTEM GROUND CHECK NORMAL OPERATION.