TBH. I think a lot of people have helped you in good faith, and with the logical root causes. You are obviously not testing things correctly or understanding what people are asking you to test.
It's not your fault, I just think you need to get hands on help from someone who is standing in front of your vehicle wth a multi meter who understands electrics.
One of the suggestions above must be the fix.
You cant be good at everything.
