Trying to import a simple notebook: none of the methods I have found are working

Starting small with regards to the %run attempts…

You should be able to run notebooks from inside another notebook using %run.
Does using %run to run an external notebook that is in the same directory as the notebook you are currently running work for you normally? I see a lot of red flags in your code and notes in the error report you aren’t paying attention to, but maybe you have %run working in other context so I wanted to check before a I posted suggestions based on that and things I cannot test myself. Sadly I cannot test because I use Unix and not Windows.