As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 7937 - OKC - CREW RECEIVED AN AIR/GND FAIL MESSAGE ON THE EICAS AND THE GEAR HANDLE WOULD NOT MOVE. MAINTENANCE REMOVED AND REPLACED BOTH NLG DOWNLOCK PROXIMITY SWITCHES AND PERFORMED AN OPERATIONAL CHECK OF THE LANDING GEAR EXTENSION AND RETRACTION SYSTEM WITH NO DEFECTS NOTED.