Buyer received item 27 days ago and the item was brand new in a sealed unopened box

Question

Now they are saying the item doesn't work and want to return it

comics-scifi-collectibles · Answer

@chewbacca415 Buyers have 30 days from the date of delivery to return an item. New items can be defective too, or it could have experienced damage in shipping.

If the buyer files a refund request saying that the item is not as described then you need to accept the return and issue the return shipping label.

Your return policy only applies if the buyer files a buyer's remorse return: Doesn't fit, changed mind, etc.

If you do not accept the return willingly then the buyer can ask eBay to step in and forces a refund. You do not get your seller's fees back, you get a defect and the buyer may be allowed to keep the item.

If the buyer abuses the eBay MBG in some way then you can report them but it doesn't get your money back:
https://www.ebay.com/help/selling/resolving-buyer-issues/report-issue-buyer?id=4084&st=

Sellers have protection for return abuse if they offer FREE RETURN shipping on their listings OR if they are a Top Rated seller and offer 30 days or greater returns. The seller can then reduce the refund amount by up to 50% if the buyer sends a different item or somehow reduces the value of the item.

Seller protection:
https://www.ebay.com/help/policies/selling-policies/seller-protections?id=4345&st=1