What next?

Step one, as everyone has started troubleshooting on, is to get your temperatures and humidity where they should be, and make sure the hides are right. Those are the three most important things to a ball python.

Step two, take a fresh fecal sample to a vet, and get a parasite check done. Internal parasites can cause snakes to be irregular, poor feeders, so ruling them out is ALWAYS a good idea when you get a new animal that doesn't eat well.

have you tried calling who you got it from to see what they were feeding it.if you havent id be doing that first then i would consider trying what they were feeding it.if still nothing after raising the temp and adding a hide box and everything else try asf (african soft furs)balls love them and they are easy to switch them off to reg rats/mice in most cases

My personal experiences with ASFs haven't been so perfect. I tried one with one of my mousers...she took it, but then refused the next time I offered one, and went back to mice. lol.