As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GEAR DISAGREE WARNING MESSAGE ON TAKEOFF GEAR RETRACTION. HAD TO RUN QRH PROCEDURE AND PULL MANUAL GEAR EXTENSION HANDLE. RETURNED TO LAX. FLT# 5623 CLOSED FOUND ELEC CONNECTOR ON NLG DOOR SELECTOR VALVE DISCONNECTED. CONNECTED CONNECTOR AND INSURED LOCKING MECHANISM WAS SECURE. PERFORMED GEAR SWINGS AND OPERATIONAL CHECKS IAW AMM.OPS CK GD, NO DEFECTS NOTED.