This guide?
I just used it yesterday on a new computer, so fresh install but older firmware on the PM3.
It worked fine.
Try again from scratch. (delete what you have done)
Follow it through word for word
copy and paste commands.
If it works then PERFECT, Job done.
If you get an error, or you don’t get the “correct” result.
Stop and update this thread, and somebody will help you through the issue…