You've gotten good advice about temperatures. Many reptiles will not eat if they don't have access to the right temperatures for digestion; but another related reason is that if they don't feel they can safely move between different temperature zones to thermoregulate, that might count as not having access to those temperatures.

With a baby in a 40 gallon tank, she might also need more visual cover, such as tubes (paper towel and toilet paper tubes are great for babies) and foliage (real or fake) so she can get from one side to the other without being too visible. It might help to cover all sides of the tank, even the front, with paper leaving just small gap or window so you can see in. Also cover the top so you're not a looming presence overhead. When my BP was a shy new baby, he refused a meal or two and the thing that got him eating for me was covering the front of the tank except for a small gap to see through. He's an adult now and not nearly as shy as when he was a baby, but he still does not care for being watched while he eats and I swear he can tell when someone across the room turns to look at him.

And when you warm up the prey, make sure you warm it up to around 99 degrees. Ball pythons use heat to target their prey, and many won't know what to do with a prey item that isn't the right temperature. Some people find it helpful to make the head warmer than the rest of the body. You can warm it up with a blow dryer, or by putting it in a ziploc bag to keep it dry and floating it in warm water.