As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IMMEDIATELY AFTER TAKEOFF, LG AIR/GRD FAIL CAUTION MESSAGE DISPLAYED ON EICAS AND PITCH TRIM MAIN INOPERATIVE WARNING MESSAGE. PITCH TRIM RUN AWAY TO NOSE DOWN. R & R THE BACKUP TRIM SWITCH AND OPS CHECKED IAW AMM 20-13-05. OPS CHECKED GOOD. COULD NOT DUPLICATE. R & R LGEU AS PRECAUTIONARY MEASURE.