Do not assist, assist feeding should be done as a last resort and you are not there yet.
I would put him in a 6 quarts tub, on aspen, give him a week with NO handling than offer food (live hopper mouse)
While 10 gallons tanks work for some animals with others it doesn't and since your priority is to get this animal to eat my suggestion would be to get this animal in a setup that is as close to what the breeder setup was, the aspen will also help with security.
Than once he eats with consistency if you want to move him back to his 10 gallons tank do so.
As for feeding f/t try converting him after he eats with consistency, well established animals with a strong feeding response are easier to switch.