HELP Please! Installing an updated system onto MacbookPro but I think I have destroyed the entire thing!

So, I am simply a person who received two older MacBooks from my mother and was looking to upgrade the system. I used OpenCore on one of them with no issues (originally MacOS BigSur ) but when I moved onto the older one (originally MacOS X El Capitan ) everything fell apart. I don't know much about computers so I fear I've completely ruined any chance of using this computer. I will do my best to explain what has happened so far but please be patient, as I truly have very little knowledge of what I am talking about.

I followed the instructions, installing the OpenCore Legacy Patcher and then the installer to my 1TB external hard drive but when it came to installing the Ventura update (the newest one that would work on the computer), I kept getting stuck in a loop with the recovery page. After multiple restarts and letting it do its thing, I eventually erased the disk. This may be where everything went wrong and I may be complete idiot for trying it but I couldn't get past the recovery page.

With the external disk unplugged, the computer was able to recover the original system and from there I started over.

Unfortunately, I am stuck in an even worse position now. The same loop but when I tried redoing what I did before (erasing the internal disk) I didn't get the same result. The screen is grey with the "don't" symbol in the middle if the hard drive isn't plugged in. Even if I try to pull up the recovery page, nothing happens.

I am at a loss and would love if someone could just tell me what to do. I would love to have an updated system on the computer but at this point, I will take the old system if I could just get the thing to turn on...

Also, this is my first time trying to use Reddit, if I'm in the wrong place please don't just delete this. Point me in the right direction first!

Thank you!!

Author: @No-Echidna-2238