Lots of people saying eBay only sides with the buyer. But they sided with me as the seller.
Sold a GPU. Buyer tried to return it after the 30 day grace period saying it didn't work. I was pleasant with communication and eBay / PayPal refused to take it any further.
However, this doesn't appear to be the norm so always be careful.
Things like taking pictures / video of item serial numbers and the packages etc will help you a lot. I've had a lot of people over the years try to return a broken electronic item that was actually their original which they swapped with their new purchase for me.
Good luck.
That was the reason why eBay sided with you. If the buyer had opened the claim on the 29th day at 23:59, eBay would have forced you to accept the return, unless you drag the buyer to say something to prove they are lying. Once a buyer opens a claim though eBay, they can no longer open a claim through PayPal. Pictures and documentation will only help you win an appeal AFTER the fact, unless the buyer is claming a defect that is shown in one of the listing pictures and stated in the description.