I'd agree. If the MacBook is beeping when you press the power button, that means the RAM didn't pass even the most basic testing done by the EFI at POST.
And since we're dealing with ebay here, just because it has a Hynix label on it doesn't mean it's actually Hynix RAM. It could be some cheap knockoff or someone selling RAM that failed QA testing at the plant and was supposed to be disposed of. It happens all the time, particularly with memory cards, but you name it, there's probably someone selling fake versions of anything you want on ebay.
Also, just to help you out in the future, you have a Mid-2010 MacBook. Doesn't matter when you bought it, when it was manufactured, it's a Mid-2010 model. That was the end of the road for the MacBook line, now being replaced by the MacBook Air 11" as the low end model.
I'm not sure what the max CTO options were for the Mid-2010 MacBook, but 8GB might be pushing it a bit. If you go to Apple's support page, and then go through their product selector to find yours, there should be a table with descriptions of the different configuration options Apple offered. If the CTO column doesn't list 8GB of RAM or higher, then the results you can expect will be unpredictable. It may work fine, it may be fussy, it might not work at all.