As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED SHORTLY AFTER T/O, RT REV UNLOCKED AMBER MSG APPEARED AND RETURNED TO FIELD AFTER COMPLYING WITH QRH. AIRCRAFT LANDED WITHOUT INCIDENT AT DAY. MAINTENANCE DEFERRED THE RT THRUST REVERSER. AIRCRAFT WAS RELEASED FOR SERVICE.