I sold a print cartridge on Ebay recently which I'd bought from Asda, opened and then realised was the wrong one for my printer. The cartridge was described as packaging open but cartridge still sealed.
The buyer has sent me a message saying the cartridge was open and empty. Which I know it wasn't.
So, would you ask for them to return the cartridge (postage was cheap as small enough to go as standard letter) and see what comes back (if they send another used, empty one are there any markings/serial no's which will prove it's not from the box I sent?)? Or just refund them what they paid (is less than a fiver, and Ebay will probably take buyers side if we end up in dispute anyway won't they!)?