I opened it again (stupid I know) and rolled the film back into the canister in a panic. I’m honestly not sure what happened, but can someone tell me if I ruined the whole roll?

Yes, it's ruined.

Film is light-sensitive. Extremely light-sensitive. Think about shutter speeds – a common one is 1/125 second. That's faster than one-hundreth of a second, to expose an image onto the film. How long do you think the film was exposed to light while you made the futile attempt to rewind it by hand??

Film photography is fun. But you need to be a little bit wiser. Try to use a good, working camera. Try to find and read the manual – especially around loading, unloading and setting exposure. You are going to spend an awful lot of money (and emotional pain) in wasted film if you don't even know whether the camera rewinds the film automatically or not. Sorry if that sounds blunt – that's not my intention. We are all beginners at some time.

Use the ruined roll to practice loading and unloading film. That's probably how it will serve you best now. If the film leader gets retracted all the way into the canister, there are ways to retrieve it, to practice another time.

Edit: Your camera manual is here:
https://www.cameramanuals.org/canon_pdf/canon_sureshot_tele_max.pdf
(Mike Butkus hosts a lot of old camera manuals on his website, and he asks for a donation for the service – you can consider it.)

Edit 2: I think it's worth a little bit more consideration around what happened. Looking at your camera manual, it seems that the camera doesn't have an override to rewind film early. So, (as long as the camera is working properly) you just take pictures until the roll is finished and the camera rewinds the film automatically. How does the camera know when to do this? Not by counting exposures, because it doesn't know much about the film canister you've loaded. It just continues advancing the film after each shot until it can no longer pull any more film out of the canister, and at that point, it rewinds the whole roll.

It seems that this didn't happen for you. There are two explanations – your cheapish 30-year-old camera is faulty, or else you weren't actually at the end of the roll. Remember that a 36-exposure roll of film is just a long strip of film. Depending on how you load it and how your camera operates, you may actually get more than 36 exposures out of the roll. You should continue shooting as normal until your camera itself senses that the roll is finished.

Now, by opening the back the first time, and then closing it again, your camera thinks you have just inserted a new roll. It tries to advance past the leader to set up exposure 1, but you said that the counter showed "S". The manual says this indicates the roll has been loaded incorrectly. It's hard to determine exactly what was going on here, but presumably because the camera couldn't advance the film enough, it thinks the roll has been loaded incorrectly and displays "S". Unfortunately, because your camera has no film rewind override, you are kind of stuck – you shouldn't open the back, even though that's kind of the only option the camera leaves you, and you can't rewind the film. So actually what you should do in that case is get yourself a "changing bag", and do exactly what you did (open the camera, remove the film and rewind by hand), but by using the changing bag, no light will reach the film and your exposures will be saved.