Honda foreman 420 transmission

[chevytahoe4x4]

Need some help. My son was out riding his his Honda foreman 420 ATV at Hatfield and McCoys this weekend and when the rear tires locked up. He was in 3rd gear running about 30 mph. you can hear the gears shifting with the electronic shift but it will only move in reverse. Tried to manual shift gears as well with no results. Had to ride in reverse for 6 miles. Was a long afternoon.