I agree with not going back...it just doesn't sound like a safe and nurturing way to learn.
As far as treats go, Tucker is insanely picky, too. He hates all biscuit type treats. I spent lots and lots of money trying to find treats that were healthy and motivating. What finally worked are
Dogswell Chicken Breast strips (they come in duck and liver, too, if your little one is sensitive to chicken). I break them into tiny pieces and he goes NUTS for them!
Good luck!