One thing I've found with my chicks is that if you leave the treat, turn your back and walk away, they'll eventually eat it and realize that it's nahmy!
My chicks were this way too. I've been offering them shredded boiled eggs on a plastic red lid (ziploc plastic) and when I first put in the tray, everyone stood statue still and just looked at it. I stood back out of their site and before I knew it, all I could hear was the deafening sound of peck peck peck peck on plastic coming from the brooder.
Now they know that the red tray means treat and it doesn't matter what I put on the red tray, it's treat time!!!! and it's hilarious to watch.
They will friend up if you keep handling them. Some of them. I have a couple of kids who come up and out of the brooder to land on my shoulders as soon as I take the top off.