You have to give her time to settle in. Wait a week before you try to feed her again, and only do an assisted feeding as a last resort. Assisted feedings are super stressful. BPs can go weeks/months without eating. I had a small 2010 go on a 2 month food strike and she doesn't look any worse for wear.
Give your little girl time to settle, a week with no handling or contact other than cleaning and refilling her water bowl. Then if she still doesn't eat, check your husbandry. If that is fine, wait another week and try again. Try mice and rats, live and f/t. Once she starts losing dangerous amounts of weight then try an assisted feeding.