Some keys not working on my laptop

It's an older laptop, roughly 5-6 years old. It's an HP Pavilion DV6-6135DX model with Windows 7.

Just yesterday, the keys of "S, D, F, J, K, L, ;, and Enter" started not working (I never spilled anything at all though). Since then, they have worked intermittently but getting worse to the point of them not responding at all. I have tried everything I can think of by searching online for help but to no avail. I have tried a system restore, uninstalling the keyboard driver and restarting my computer, unplugging my computer and holding down the power key for a long time, taking off the keys and wiping the area down with rubbing alcohol to clean them with a paper towel, using a blowdryer to get any type of crumbs out, etc. I don't have an external keyboard on hand to even try that option. I did run the EOS Mode or whatever it's called and the same keys didn't work on there either if that helps you.

I don't have QTips or a can of air to try getting even more in depth but I'm not even sure if that is the problem anymore.

Can anyone please help me troubleshoot this? I went ahead and bought a replacement keyboard on Ebay for $18 but I'm not even sure if that will work. I have to learn how to install it myself, don't know how to do that either.

Please help!! Thanks.