you just have to pop off the grills, and the left and right part of the system are tabbed together. you do need a torx 8 or 10 forgot which to open up the screws (only take out the long ones). you don't have to remove the rf board, which is another screw gauge iirc. it's been years since I've opened a phat, so this is based on memory.
I've got it to this....can I just remove the T screws on the top to see what i need?