Start a new post. You jumped into a post that was already in progress so no one knows what you did and why you did it.
Do not waste time trying to test different pins because unless you know what values should be at the pin, it doesn’t tell you anything. Bambu Lab printers are closed source and they (as far as I know) don’t put information out like that because it tells competitors how the machine works.
One top of that, the boards are cheap. Just buy the two boards that the cable connects to.