As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE FLIGHT NR 2268) THE CREW REPORTED A AIR/GROUND FAIL MESSAGE AFTER LIFTOFF. THE AIRCRAFT RETURNED TO CLE AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED AND REPLACED THE LANDING GEAR ELECTRONIC UNIT AND THE NOSE GEAR WOW PROXIMITY SWITCH HARNESS. OPERATIONAL CHECKS WERE GOOD.