You do not state whether this is a public or private school, or whether you signed any contract for this. Generally, schools have a lot of power. Despite lack of funds to educate, they somehow muster it for litigation. So, if the goal is to graduate in the ceremony, pay the bill with a statement it's disputed and paid without waiver or release. Then go after the school if you have a basis. An attorney would have to review whatever documents you may have signed for the laptop, etc.
