Non working return

[doctor.bertie-mushroom]

I recently sold a modified ( silent ) AirTag via eBay , I have sold numerous previously, and I always take a pic of the serial number and send this to the buyer ( the serial number is not on the actual device , but shows on the phone screen ) this is to prevent people “ exchanging “ items . Anyway, the buyer contacted me and said “ it wouldn’t work with his Samsung ?? “ , obviously! 
Ebay said he’d changed his mind about the item , two completely different reasons in my book , but I accepted the return and notified the buyer I would issue a full refund once I’d checked the serial numbers matched . Well today I got the return and it is completely dead , I’ve tried  a new battery , nothing !! 
Obviously now I cannot check serial numbers , what can I do guys ???

Thanks in advance 

[*vyolla*]

Not much you can do here except to refund, to be honest, it's not impossible that the item is faulty.

You can report the buyer, but this won't change the return situation, you'll still need to refund.

https://www.ebay.co.uk/help/selling/resolving-buyer-issues/report-issue-buyer?id=4084&st=3&pos=2&que...

If you're modifying these items yourself then you should really list them on a business account.  I'm pretty sure that these aren't allowed and that Apple can sue you for this, you might want to check that out.