Most states have a merchanability law for consumer goods. This is in addition to any warranty from the manufacturer. A product must be suitable for the use that is intended. A major flaw in the design (square wheels, a battery that lasts 2 minutes etc.) is covered by this law and would get you your full purchase price back and you would likely not have to pay shipping. To enforce it though you would have to go to court (small claims or other). If a group of owners all had the same problem they could do a class action.