As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED LEFT THRUST REVERSER UNLOCK MESSAGE IN FLIGHT. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT, FOUND A DIODE WITH AN OPEN CIRCUIT, R & R DIODE TERMINAL BLOCK AND PERFORMED CHECKS IAW AMM. AIRCRAFT RELEASED FOR SERVICE.