Car Repair Service - Customer Refuses 2 Pay - Can the Police make u give a customer their car if they have a remaining balance?

My husband is a Toyota Certified mechanic and installed a motor for a friend of a friend. Well, the dude only paid half and wants the car ASAP.He is saying that he'll call the police and report the car stolen if we don't give it to him. He text this, so we have all his text bout the car, plus we have a great security camera system around our whole house with him talking about the car and payment, etc.. Can the police make us give him the car back without him paying the remaining balance??