So it appears that there is a magnet in the lid of the laptop behind the screen. 

I have been able to determine that it is not to secure the lid when closed, and it does not seem to be a screen switch for when the laptop is closed. What is it?Tall rectangle in the boxed area appears to be the magnet.

In this picture from the service manual you can see the magnet in the boxed area, it appears to be the tall rectangular piece.