As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED LT THRUST REVERSER UNLOCK AMBER CAUTION MESSAGE AND THAT EMERGENCY STOW DID NOT WORK. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT, R & R LT POWER DRIVE UNIT AND PERFORMED CHECKS IAW AMM. ACFT RELEASED FOR SERVICE.