Its a VGS50 valve guitar system.

None of the effects work kind of and it makes a strange screeching sound when its plugged into an amp and turned on. Any reason why?

I can tell you anything you need to know about it; its right in front of me. Sorry I can't be more specific.. its like my first pedal board thing like this (I have single pedals..)
Yes, its multi-effect.

No, its not new. I don't know how old it is, but its in good condition.

I have a first act thing, and another amp from like the 60's or something (don't know brand, but its like huge lol. The first act is small.)

I've tried reset. :/
Well, because if it was tube amp it's possible you have a microphonic tube. If it's a solid state amp, like the First Act, then don't know. It's possible the pedal is fried. I guarantee if I plugged my Multi pedal into the same power strip as my amp I would have issues. So if at all possible, try plugging the pedal into a different power source and see what happens. use an extension cord if you have too.

It's also possible the gain on pedal is cranked to '10' but now you can't access your settings. It's possible you have a faulty jack in guitar or amp, or poor grounding in guitar or amp. I'm assuming everything is OK when you plug guitar strait into amp.

Does this pedal have USB or any other way to get it connected to a PC? If so, you might be able to download a patch or fix of some kind. Mine has software that I can use to access the presets etc.

Lastly, check the manufacturers web site for patches and forums where people discuss stuff, call the company, email the company, Google it.

Good luck.