Am I in the clear for a refused return?

[sac945]

Hello, I have a question pertaining to a situation as a seller. 

On June 12th a buyer purchased a used graphics card from me. I have a no returns policy, which I assume protects me from remorse purchases as long as the item is as described. They received the graphics card on Jun 21st. This morning (July 31st) -- about 40 days since they received the item, they opened a return with the following reason, 

Reason for return

Just didn't like it

Details

The RTX 2060 slows down my system compared to my original GTX card. Bigger isn't always better with the RTX and showed slower performance.

My guess is that they used this GPU to mine cryptocurrencies with, and are now done with it and want to return it in a state that it wasn't shipped in. Furthermore, the value of this item has decreased by about 20% so I wouldn't be able to resell it for what I originally sold it for, and I already paid fees on the sale to Ebay. I declined the return, and the current status of the item says

"This return is closed

This return was closed on Jul 31.  "

Is this case closed? Should I expect any future notices from Ebay? How should I navigate this from here on out? 

Thank you 

[tdumonde2014]

You and the buyer are done with eBay. Your next problem might be with the buyer's credit card company. If they open a claim with them, you will lose your money and they will keep your item. You also be charged $20.00 for your troubles by eBay for losing the case. While you won the battle, you will lose the war.

[sac945]

"Your next problem might be with the buyer's credit card company. "

Thank you.

I am hoping this doesn't happen, but if it does, I'll probably abstain from using eBay in the future. I am not a business and I am only selling my used stuff from time to time. Probably will stick to in-person sales in the future. 

Sad that buyers have so many options, but sellers none. 

[tdumonde2014]

Certain items are magnets for scammers, graphics cards being one of them. Good luck.