Have you read eBay's Money Back Guarantee for buyers from a seller's perspective?
It doesn't really matter whether the buyer's claim is false or not. Once the buyer opens that item not as described case, you, as the seller, will be required by eBay to send the buyer a prepaid return shipping label, and to refund in total when you receive the return.
If you decide that you don't want the item back, you will still be required to refund the buyer.
