You have not at all specified if you are a dealer, if you sold it pursuant to a contract, if you have a return policy - nothing.  This information is very important in trying to give some guidance here on the matter. Be that as it may, if the product was damaged in transit back I would refuse to reimburse the purchaser at this time. That should get their attention.  If you have already reimbursed the purchaser then I think that you have no alternative but to sue them for the damaged computer.  I think that they are giving you very little choice here.  I would hesitate to send it back to them and rather have you keep it for proof.  Otherwise it will be a he said she said situation.  Good luck.