Well the rules are, for a full refund for an item not as described, e.g. arived broken / damaged, the buyer has to send the item back to you at your expense to receive that refund.
This has to be the ruling because otherwise, a buyer can just claim something is broken, not send any photos / or the item back keep a good item and receive that refund.
Send them a polite message that without the item being sent back as within eBay rules, you cannot offer a refund.