You're a beginning snake-keeper, right? Besides the fact that the store should not have sold a snake that isn't eating, why on earth did you buy (or exchange for) one
that has no current record of successful feeding? This is sadly setting you up for failure, or at least a MUCH more difficult experience.
Personally, I'd have insisted NOT on an exchange for the prior sick BP, but a full refund of my money, and I'd NOT have gotten another snake from that store for
at least a year IF their methods had improved significantly & probably not even then. I understand that you are eager to have a pet ball python, but you need a
healthy snake to start with, and you need to follow the care guidelines* given here by experienced folks who know what they're doing. Sadly, just because a store
SELLS snakes does NOT mean they know what they're doing. I'm not bashing pet stores, as some are excellent & we have members here that work in stores, but
you can't assume they'll all equally safe to buy from. Your previous BP from that location was seriously ill or injured, you'll never know which, & that means their
other snakes may be as well, and just not showing it yet.
*such as allowing enough time for a new snake to settle in before trying to feed.