As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, DURING LANDING GEAR UP, WE GOT A GEAR UNSAFE INDICATION ALL (3) RED LIGHTS AND A FLASHING RED GEAR HANDLE. RETURNED TO AIRPORT GEAR DOWN WITH ALL INDICATIONS NORMAL (3) GREEN NO RED. REPLACED DEFECTIVE NLG UPLOCK ASSY IAW MM 32-322. OPS AND LEAK CHECKS GOOD.