As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON INITIAL CLIMB CREW TRIED TO BRING THE GEAR UP AND RECEIVED THREE AMBER LIGHT. CREW RAN CHECKLIST AND PUT GEAR HANDLE BACK DOWN AND RECEIVED THREE DOWN AND LOCKED. CREW DID NOT DECLARE AN EMERGENCY AND RETURNED TO IAH. UPON FURTHER INVESTIGATION FOUND MLG ALT. RELEASE DOOR IN THE OPEN POSITION. SECURED DOOR CLOSED NO FURTHER FAULT NOTED IAW Q400 AMM 32-34-01.