
Don't force the issue. Try sitting in a corner of his kennel/run with some treats, and occasionally put one on the floor,
without even looking at the dog. Completely ignore him. Let him make the moves towards you. And don't react if he's brave enough to take one of the treats and rush away with it. Just put another one down, and then leave the kennel, all without taking any notice of the dog at all It sounds as if he needs longterm rehab, poor thing.
:)