Go through Ebay first. They will open a case with the seller and can force a refund. Ebay has a product representation clause that basically say if the product does not meet what the seller said it was, you have the right to return and get a full refund. So if it's used/working and it arrives used/non-working, you get a refund. If it's new/working as stated and arrives new/non-working then the Ebay guarantee can kick in.