21-09-2020 9:13 AM
I'm very sorry, but you brought this on yourself by sending a replacement.
If you do this, you have to trust the buyer to close the case when they receive the replacement. If they don't, then as you haven't refunded the buyer, eBay will enforce a refund and place a defect on your account.
For this reason, it's always best to offer a refund on return. That way, eBay will enable you to send the buyer a prepaid return label (if you want the item back). On its return, they will process the refund through PayPal and you will receive a credit for your selling fee. Your seller performance record is unharmed. The buyer can then buy a replacement item from you, if they wish to do so.
This is best for the buyer too. We often here from buyers who have accepted the offer of a replacement, only to find that the replacement is faulty, or they're kept waiting so long that they've miss eBay's 30 day time limit to claim a refund.
I'm afraid there's nothing you can do about the defect. Your only chance of getting the second refund returned is if the buyer is willing to repay it to you.