This step is wrong. It’s actually two security brackets, not three, as long as you don’t break the one on the left/upper side. If you do it like it’s shown here you will break this part. The correct way to do this is remove the bracket on the right side, then remove the board with the other bracket still attached. Watch this video to get an idea: https://youtu.be/9o1DGKT76eo (interesting part starting at 1:50).