Have you ever tried clicker based training with a stick (I used chop sticks)? A parrot may bite down hard on the stick to start. Itāll be a really rough start depending on your parrots exposure to humans, and their hands. Does Charlie eat pellets? If you donāt feed him seed they really are incentives to at least my parrots. Nico my Ekkie āhatedā clicker based training to start. It looked a lot more brutal than it was. Whenever he lunged at the stick, and touched it with his beak I clicked the clicker, and gave him a treat. I always remained calm (yes, I had to prepare for this beforehand because I had no experience with larger parrots, and to be quite honest Nicoās huge beak was intimidating). After awhile he actually appeared to get excited for his training. He appropriately grabs the stick with his beak for pine nuts. Itās how I started to handle Nico with my hands. Baby steps! I do the same training with my conures. They both had prior exposure to hands, and humans before me.
I hope something in here helps! Hopefully you find a way to help your conure that doesnāt especially care for hands.