There are many different ways you can handle this. Actually the buyer essentially admitted to opening the wrong return reason, since he stated that it was another unit that was 'defective' only yours is more sensitive then his pleasing. I would request him to close the return as the item is NOT defective and ship it back at his cost and you will be happy to refund once returned. Unfortunately on Ebay 'no returns' doesn't mean no refunds so you are better off just accepting them. Your 'no returns' only covers buyers remorse reasons.
If the buyer declines and forces the issue abusing the MBG by claiming a 'SNAD' then accept the return, upload the return label and make sure to insure it! Don't use EBay's automated label as it will NOT have appropriate or adequate insurance, this is in the event the buyer sends something else back, more to that point in a moment. Advise the buyer in the return request that you'll be providing the return label and that you will refund once you receive the item back. Since you suspect he will return the old, defective unit I personally would state as a means of added security for both the buyer and yourself all returns are held and opened at the Post Office in company of the post master. Hopefully deter any would be liars from sending something else back in return of your item.
If the buyer would return your item paying for shipping himself you only have to refund the price of the item, minus the original shipping charge. After all you have your item back to resell, it wasn't brand new right? So you are made whole. So it is only fair they receive the full item cost back. If it were a new unit however and you offered free returns you would be able to withhold up to 50% of the refund for any loss in value, just something to think about if you change your mind about offering returns.
If the buyer returns YOUR item under the SNAD return appeal to Ebay showing them the messages where the buyer admits to making a mistake confusing your item with another. Also make sure to report them for abusing EBay's MBG and add that buyer to your BBL. If they were truly an honest person they would have cancelled the request and maybe asked to return with them paying the return cost. You may have to call into Ebay, may even take a few phone calls as not all CSR's will assist. The main thing is to have the policy in front of you and reiterate it back to them if you have to. While you should have to refund if you receive your item back it is not fair that you should lose the shipping cost both ways for a dishonest buyer.
If the buyer would return the defective item even though you advised you would be having the package held and opened in front of the post master, which by the way can be a total bluff you don't actually have to do that, then you'll want to take the appropriate measures. Just as precaution message the buyer and inquire if it was a 'mistake' as you received the old, defective unit back rather then yours, and advise the buyer if they did send the appropriate unit you'll be opening a postal investigation. This is why you need the insurance, if you receive anything back other then what you sent file the claim, I have actually done this citing items incorrect/missing. Also report them to Ebay for abusing the MBG, file a mail fraud report and file an internet fraud report at ic3.gov. Personally I would tell a buyer this is what I am going to do to you but then I have no patience for lying, thieving lowlifes. Take those reports and appeal to Ebay, again if you get a CSR that isn't accommodating then hang up and try again, maybe ask for Trust & Safety as they are more adept at helping with those matters. Make sure to have the appropriate policies in front of you and definitely don't let anyone run over you!
Don't worry so much about your feedback, Ebay doesn't evaluate you any longer based upon your feedback and most buyers I think understand that you can't always please everyone. There is always going to be that 1 person, or even a few, out there that you simply cannot appease. Personally, and I think most, look at how a seller responds to that bad feedback and makes their decision based solely from that. While getting 1 bad feedback sucks sometimes, it certainly isn't going to massively hurt you. As stated, Ebay judges you based off your seller metrics now. So long as you don't have excessive returns, returns they've have to settle for you and you are shipping within your handling time, etc.. you are all good!
Good luck with this buyer, I truly hope they do the right thing but in the event they do not hold NO mercy lol! Come back and let us know how it goes 🙂
