Remove the two rubber feet on the front.

Remove eight screws. The Manual says seven, but in my Laptop there was an additional screw hidden under a sticker on the lower side.

Remove seven 1,6x2 screws from the battery compartment.

Remove three 2,5x3 screws from the HD area

Remove two screws: One near the small backup battery, the other one from the left part of the service bay.

Now you can remove the base enclosure.