My Steam deck apparently had a different shield (probably upgrade to make sure there's no issues with the fan cable) there were just the two screws on the left side and there was no screw under any piece of foil tape (no foil tape at all) and the shield was black made it somewhat easier. Also when removing the board shield it can kinda be stuck due to cooling pads attached to the shield, just wiggle evenly from all sides pulling gently upward and it will get loose eventually. This makes sure the shield doesn't get bend.