Image borrowed from here which gives great insight into what could be the cause of your garbled video on your SNES or SFC and the various possible modes of failure.

You’ll see it is actually a Nintendo Super System, which I had never heard of until a few minutes ago reading through YouTube comments - thank you to whoever pointed me to this site and a big thank you to DogP for keeping a repair log as detailed as they have!

Actually, this might be useful in working out some circuit bending for the SNES… stay tuned! 😉