eBay will make you refund. I had a similar situation and all the buyer has to do is send it back and show ebay it was delivered back to you. If they open a case and provide tracking and it shows delivered you take the hit no matter what. I received a return randomly, no contact from the buyer. Next day a case was opened and tracking was added. eBay sided with the buyer even though I had no returns.
4/9/14 at 7:57pm