your solder/unsolder instructions are fine, thanks.
I had to change my Upper Left Button as well. It was broken now for the second time.
You have to very careful if you lift the button during unsoldering as it is possible
that the solder point on the other site may break and you lost the electrical connection.
Better is to fix the board and use a friend to unsolder both sides together.
Or we need to know which is the side where the electrical connections are made and start unsoldering there.
The “dummy” pads are not so important if one of them breaks.
Please could you offer the electrical plans?
And put all spare parts in one post.