As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED A "TCAS FAIL" ANNUNCIATION ON THE PDF AND TCAS TEST FAIL AURAL ANNOUNCEMENT DURING PREFLIGHT TESTING. OPERATIONS WERE CONTINUED PER MEL. THE MAINTENANCE VENDOR RESET THE TCAS CIRCUIT BREAKER AND PERFORMED FAULT DIAGNOSTIC CHECKS, COULD NOT DUPLICATE ANY OF THE RECORDED FAULTS. PERFORMED GROUND OPERATIONAL CHECKS OF TCAS SYSTEM. THE AIRCRAFT WAS RETURNED TO SERVICE