Step 19
Remove the small greasy springs with white plastic caps from either side of the battery contacts.
Step 20 — Upper Case
All of the screws in the following step have small heads - the screws with larger heads hold the bottom shield on.
Remove the following 9 screws on the bottom of the computer:
Three 3 mm Phillips around the battery compartment.
Three 5 mm Phillips on the left and bottom edges.
Three 14.5 mm Phillips on the top and right edges (you may have to peel back the foil tape to reveal the screw near the security lock slot).
Step 21
Turn over the computer and open it.
Remove the following 3 screws on the edges of the keyboard area:
Two 6 mm Phillips underneath the keyboard area.
One 9 mm Phillips above the keyboard area.