Issues with GameCube Controller (Many Details Inside)

I've been trying to hook up a GameCube controller to an Arduino Uno to create Xinput instructions for a school project. I've been following instructions and using the library built by NicoHood on GitHub. I've dissected a controller, figured out which cables go where, but I am still unable to get the code to output anything other than "Error reading Gamecube controller." I've dumped hours upon hours into this, tried swapping out controllers, logic level converters, tried different cables, and so on. I've completely exhausted my pool of ideas, and was hoping someone could give me a hand. I've included some images which show exactly where I am at right now.

The data lane on the board goes from 3.3v to ~1.9v when plugged in. This leads me to believe that the controller ITSELF might be working properly (1.9v seems roughly to be how the data packets should look like on a multimeter?). Everything else seems to read properly, 5v going through the 5v line (3v line seems to let through SOME power when 5v is supplied, maybe some internal circuit in the controller for converting voltage?).

If you need any information that might help, PLEASE let me know, I'm still a huge noob in this world.
Thanks in advance for any help.

Here's the code I'm running: Nintendo/GamecubeController.ino at master · NicoHood/Nintendo · GitHub

If you need any information that might help, PLEASE let me know

The code that you didn't post doesn't work. Doesn't that suggest something to you?

My bad, I've just been using various examples on the creator's repository. Link
Updated in main post.

Updated in main post.

No, you added a link to some site where you stole some code. That is NOT the same as POSTING YOUR CODE.

PaulS:
No, you added a link to some site where you stole some code.

"Stole" is a bit harsh, but the essence of the message is "please post the program here"

...R