Broken HDD Connector to Broken Logic Board? Whats really the problem?

I got a Macbook Pro 2 years ago and last April it started not booting up properly, it just showed an icon of a folder with a question mark and then shutting down. I took it to a repair shop (not on an Apple Store since I was out of warranty already) and they said that the HDD Connector/Cable was broken, and that it needed to be replaced. I didnt replace it yet then because I didnt have the money to replace it. Then my mom took it to another repair shop and they said that the logic board needed to be replaced.

My question is, what really IS the part that needs repair? My Hard Drive was fine when the repair shop I went to booted it on another computer, the only problem that I had was my Macbook Pro not booting up properly and the folder icon popping up. Also, it can still charge, but when I power it on and turn on the Caps Lock, the light for it wont turn on.

Other details that might factor into what went wrong: Spilled some oil into the keyboard a few months in when I got the Macbook, and the left arrow button wont work anymore. But other than that, everything was fine.

Also: I tried every reset that’s possible, and nothing works. The keyboard isn’t responding, but I don’t know if thats because the keyboard is broken, or because the HDD Cable/Logic Board is.