As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
GARMIN GTX345 TRANSPONDER FAILED ON TAKE OFF. "XPDR FAIL" CAS MESSAGE. TRANSPONDER SEEMS TO HAVE QUIT COMMUNICATING WITH G1000NXI SYSTEM. PROBLEM CLEARED WITH POWER CYCLE OF G1000NXI SYSTEM. INTERROGATED TRANSPONDER WITH TEST SET IN AIR AND GROUND CONDITIONS AND MODES A,C AND S WITH NO FURTHER PROBLEMS NOTED