24 pin connector fried, mobo or psu problem? Ebay seller

Hey, have an issue with an item I sold. I sold a motherboard and the person I sold it to fried his 24 pin connector to the motherboard. It is not my fault, the board was good condition when I sold it. I talked to one of my friends who graduated University of California in Electrical Engineering and said it would be the power supply. I would like your opinion. Even though he is specialized. The buyer wants be to refund him his money and I do not believe I should becuase I did a stress test with the board for 24 hours with games and other software. 

A frying of the 24pin connector usually comes from a bad connection between the PSU and the Mobo and/or the PSU itself not operating properly (aka being dodgy)

It is quite likely he may be using a cheap PSU that doesn't create a solid connection and hence burns the connector out.

EDIT: Or a less likely situation is when using multiple GPUs and not having an external power input (like a molex or 6pin by the PCI-e lanes) causes too much strain on the 24pin and burns it out also.

You'll lose.

Ebay/Paypal always sides with the buyer. Unless there are special, provable circumstances. Like you had a video of it working, you taking it out of your PC, and boxing it up with the shipping lable.

Even then they would probably side with the buyer.

Yes you lose. I found out just the other week that the guy I sold an ASUS R9 280X DCUII V2 TOP to burned it out after a month mining, wanted a refund, Complained to ebay and got it. Dosent matter now that he admitted to killing it (He did a power mod that fried the GPU during mining) Ebay wont listen to me. The best they could do was remove the black mark from my account. I still have the bad review though. And im still out of pocket over $500

That's unfortunate. I'm glad I sell items on this forum.

Did you sell the item as having no warranty and that you did not accept returns? If you did, then you are fine.

Also if it was fine before shipment and you have proof of him saying HE fried the connector in the board then there shouldn't be a problem.

I do not ever except returns on hardware on ebay, because how easy it is to mess up hardware to begin with.

Next time I will have to do that, ebay I feel I always get ripped off.