As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO PLATFORM DUE TO DURING TAXING, THE EICAS MSG RADAR FAIL WAS SHOWN. DURING MX REVISION, THE TEST SWITCH OF THE WEATHER RADAR CONTROL PANEL WAS DETECTED STUCK. THE WEATHER RADAR CONTROL PANEL WAS REPLACED IAW AMM 34-43-91, TESTED CORRECT.