If you got scammed, take it up with ebay, or paypal, or the seller.
I'm sorry this happened to you. You lost $660 because you bought a damaged unit, and didn't immediately take it up with ebay. This isn't GPD's fault. The buttons they used, has nothing to do with you buying a damaged unit.
I've taken my win2 apart a few times, and had no problems with anything breaking. I regularly work on laptops, so working on the win2 wasn't much different.
Again, there is no business between you and GPD. This is between you and the ebay seller. Personally, i don't want GPD to humor you with a new unit for free, or even an exchange. This has nothing to do with them, and they shouldn't pay for this. So go get a refund from the ebay seller. If you can't, or won't. Then tough cookies, you're out of luck. This is the risk of buying from ebay.