Step 19
Once the front and sides of the lower case are free, turn the computer so that the back is facing you and pull the lower case up and toward you until the back tabs pop free (it may be helpful to jiggle the case up and down).
Step 20
Remove the small greasy springs with white plastic caps from either side of the battery contacts.
Step 21 — Upper Case
Remove the following 4 screws on the bottom of the computer:
Two 3 mm Phillips from the left side of the computer.
One 4.5 mm Phillips near the latch mechanism (this screw may be missing in 800 MHz iBooks)
One 14.5 mm Phillips near the front, right corner.