"On the next episode of Deep Space Nine! Tensions rise when Miles O'Brien's wife is possessed by a sadistic, emasculating space demon, and he can't tell the difference."

I'm sure there's a valid reason, but I've got no idea what it is. Why "Kelvin?" Is that a reference to a character in the original Star Trek continuity?

Okay, so you know that iMac (mid-2011 model) I rescued from a thrift store for fifteen dollars? After some struggling and a little panic about the screen not working (it was just a cable that disconnected, no biggie), I got it back up on its feet. Hooray for me!

There's just one problem, though. What the heck do I do with this thing? I gave some thought to turning it into an emulation station, but I'm not sure that a machine this old would be much good for 21st century console emulation (ie PS2, GameCube). I tried installing Dolphin for testing purposes, only to be told that the OS (El Capitan) was too old and that I'd need to download a legacy version instead; one that's likely less optimized and slower than the latest ones.

I've been doing some research and have discovered that this iMac can run a more modern OS, Catalina, with a patch. Would that newer operating system even be feasible on such an old system, though? Years ago, I bought a netbook that someone foolishly installed Windows 10 on, and it was dreadfully slow. (The previous owners put Windows 10 on a damn netbook. What were they thinking?!)

Also, I'm quickly discovering that Mac OS doesn't work the same way as Windows. When I downloaded and installed the Dolphin software, it just plopped it on the desktop, rather than letting me specify a folder and then creating a desktop shortcut to it. Is there a guide somewhere that would help guide me through the differences? Windows is intuitive for me after using it for a quarter of a century, but Mac OS, not so much. I think I'm going to need a Mac for Dummies book to really feel comfortable using this thing.

Thanks in advance for any help you can offer!

EDIT: This wasn't mentioned in the original post, but I wanted to clarify that I've already put an SSD into this system. It's the reason I had to open it up in the first place... and then put in the terrible, terrible screen screws. (Ugh, I'm still having flashbacks.)

Okay, so I got one of these at a thrift store for $15, and had the galaxy brain idea to open it up and swap out the old plate hard drive with an SSD, even though I don't have much experience repairing Apple devices.

You quickly come to the realization that while these machines are user-friendly, they're very UNfriendly to repair. There's a glass cover for the screen which must be suction cupped off, and eight Torx screws holding the display in place. When the screws are removed, they're quickly grabbed by the (STRONG!) magnetic edges of the system, making them an absolute "joy" to deal with. And what's worse, there are four data cables on the display, all difficult to reach. I accidentally pulled one of these out while reaching for the other three, and I'm a little worried that I may have damaged it. (It's the flat cable attached to a bronze connector, likely the screen data port.)

Anyway. I put the crazy thing together, and while I can hear it boot and the fan spin, the Apple logo does not glow white and the display does not turn on. So I'm a little worried I may have screwed myself on this attempted repair.

My two questions are this:

1. Does anyone know the specific size and thread of the screws around the edge of the display? I'd like to swap them with something that isn't magnetic, and I've heard brass screws will do the trick.
2. Next time I open this machine, I'll check the four display cables to make sure they're properly connected, but... what recourse do I have if the cable and/or connector are damaged? It seems like a display or motherboard swap would be necessary, and it's hard to justify that for a $15 computer, as much as I'd like to bring this back to life.

Thanks for any help you can provide, and my apologies if I've put this in the wrong magazine.