They're quite nervous animals, being a prey species, so the best way is to give them some time and let them do things at their own pace. As long as he's eating hay he'll be ok.
Try sitting in there in absolute quiet, sit over the other side of the room and read a book or something, eventually he should start to feel safe enough to come and explore. If you have treats with you he may feel safe enough to take them if he "finds" you and them on his own terms.
If you're offering them to him in the cage it would be a little bit like if you got abducted and then the abducter shoved some food in your face, even if it was your favourite food you'd probably be very wary of eating it. :lol:
ETA: and if you have lino flooring, or anything potentially slippery like that, then yes he may feel a little uneasy on the flooring. Try putting down some rugs
