As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 2820 - EWR - DURING CLIMB LANDING GEAR WILL NOT RETRACT - AIR/GROUND FAIL. FLIGHT CREW PERFORMED AN AIR RETURN AND LANDED UNEVENTFULLY. MX PERFORMED TROUBLESHOOTING AND FOUND LGEU FAIL. MX REMOVED AND REPLACED LGEU AND PERFORMED OPERATIONAL TESTS SUCCESSFULLY. ACFT WAS APPROVED TO RETURN TO SERVICE.