Congrats on the snake!

Ball Pythons can be picky eaters. The transition from live to f/t can be a tricky one at times. You have the right idea getting it warm. Next, I would give it a little action, like you are fishing with a lure and trying to coax a fish to strike. Sometimes it just takes a little extra work.

I also agree with leaving it in there overnight, it won't hurt anything.

BP's can go many months (6-8, sometimes even more) without eating. It's not exactly healthy, but it isn't deadly either. Keep at it, you may have to be very persistent.

Let us know how it goes.