Start by disconnecting everything, cables, battery, etc.

There are three hex-shaped screws holding the board, which are right where the CPU was. These also provide the screw holes to screw and hold the CPU. Use an English 1/4" size socket to remove these three screws left behind from the CPU.

Then remove the 4 screws which are located around the edge of the board. If you have less than 4 screws, don't worry too much, if you don't have trouble removing the board at the next step, then you are fine.

Now, slide the logic board away from the rear of the case about 1/2 inch, and lift it out. It should not be difficult to pull out or up, if it is, go back, and make sure you have removed all screws. I did, however, have to pull out towards the front, then up, then back towards the back of the case before I could completely remove the board.