Sorry to hear that. I can't believe how much that chicks leg was able to rotate! Slipped tendon chicks are difficult to treat and are time consuming but for me I can't do nothing without at least trying. I had a chick that had slipped tendon last year and that was my first time dealing with it...
Okay I think you need to try a different splint. Do you have a small hair band? You don't want it to be too loose or too tight. Here's a pic of one I made from a hairband and you just slip it on their legs. I think you might have done the band-aid too high that may be why it's immobilized...
That looks like slipped tendon unfortunately. Here's some videos I found helpful when I had to go about that. Do you have to self-adhesive bandage or medical tape to wrap it back into place once you have the tendon set right?
Great job wrapping and taking care of the slipped tendon chick! I had one hatch out with slipped tendon a couple months ago and it is a hard thing to deal with. That's so exciting it can walk on its own!