What if anything are you using to measure temperatures/humidity?

Coming from petco, your snake has very likely been underfed it's entire life. You can try offering a mouse hopper, or rat pup tomorrow (mouse pinkies and in most cases mouse fuzzies are way too small for any BP) but don't be too surprised if your snake doesn't eat. many times a BP will need some time to settle into a new home before thy will start to eat. Keep to the weekly feeding schedule. If your snake refuses a meal they don't get food offered until the next weeks feeding day. Offering food too often can actually stress out a BP and result in more refusals.