That isn't how it works. The reason the flashcart does not show up is because it isn't actually a flashcart once b9s is installed to it. It's a cart with a firmware on it. There isn't an icon or game to boot to, so it doesn't show up. That cart will work in every single 3ds you put it into guaranteed, and you can restore it to back how it was with a backup of the cart's firmware you were supposed to backup beforehand.