No movement

[Bogertophis]

We need more info, & it would also help to post pics of your set-up if possible.

What are the temperatures- lowest, highest ("hot spot")- and where she is parked (in relation to the warmth)? What kind of enclosure? How cold is the room it's in? Is it a quiet location?

Is that all you're using for heat- just an overhead "heat-lamp"? How much light is she sitting under? Few snakes appreciate a lot of light, so you might be better off using a CHE (ceramic heat emitter- similar to a light bulb except it doesn't put out any light) or a red or black incandescent bulb for a lot less light. No snake should be under a bright light for 24/7.

Does she have at least 2 hides? (one cool side, one warm side) How large are they compared to her coiled up size? BPs are snakes that like to feel "back pressure"- to be cozy & snug in their hides so they know nothing can sneak up on them- ie. they're safe. What KIND of hides are they? (ie. open-ended tree bark tunnels don't offer security- they're okay as cage furniture, but don't really count as "hides".) Hides should have one door only, just big enough for a snake to fit thru after a meal, & they want a low ceiling.

How are you taking the temperatures? (they need to be accurate).

How old is she? Do you have any history on her? When did she hatch? What she was eating before you got her? For best results, offer the same size & kind of prey & in the same way- ie. mice or rats, approximate size, live or frozen-thawed ("f/t") or fresh-killed ("f/k"). How you offer food can either entice a hungry snake to eat or scare them into refusing; BPs are often fairly docile, so a rodent that appears to come AT them would not be natural & would scare them. Make sense? A slight jiggle to elicit a chase from the snake is far better than too much motion.
Use feeding tongs to offer & never take a snake out of their home to feed in some other side cage.

What time of day have you tried to feed? BPs usually feed best in evening/night hours.

How often? If your snake refuses food, don't keep offering as that only stresses them to refuse even more. Wait at least a week before offering again, & after several weeks, maybe wait 2 weeks before offering again.

What is the snake doing when you tried to feed? BPs are ambush-predators- they don't actively hunt for their food, they wait where they feel secure (often peeking out of their hide) until some "clueless prey" happens to pass by them within reach- within striking distance. Don't bother trying to feed a BP that's roaming their enclosure- they don't feel secure enough to eat then.

Humidity: can be a challenge, especially in winter (our heat & A/C removes humidity from our homes, even in humid climates). The kind of substrate you use can make a huge improvement on humidity; you can also add a "humid hide". (Ask if you don't understand what that means.)

BPs: in general are not active snakes- they tend to stay put more than many other kinds (making some ppl call them "pet rocks"), but a snake that's newly acquired will also be confused & fearful for a while- they do need time to settle in. Older snakes often take longer to adapt than young ones (how old is yours?).

Winter temperatures- if your snake was exposed to chilly temperatures, that could make her hesitant to accept food too, instinctively.

What other kinds of snakes do you have experience with?