When you put her in the box how long did you leave her alone? You might want to leave her alone overnight with the prey. She probably became more frightened when you opened the box and made her meal come "back to life".
My female pastel stopped eating for a month, I had to feed her at night with no lights on except a small flashlight so I could see what I was doing. She's eating like a champ now.Oh, I also ended up braining her first few meals back which seemed to help stimulate her feeding response. Good luck, but don't get too frustrated, she'll eat when she's ready.