Remove the following ten screws securing the lower case to the upper case:

• Seven 3 mm Phillips screws.
• Three 13.5 mm Phillips screws.

Using both hands, lift the lower case near the vent to pop it off two clips securing it to the upper case.

Remove the lower case and set it aside.

Three special five-point Torx screws secure the battery to the upper case. They can be removed with this special driver.

If you don't have the special 5-point tool, a common 1.5 mm flathead screwdriver can be used in a pinch. Be sure the head of your flathead screwdriver fits snugly across two of the five "points" of the screw head before trying to break the screw free, as a loose fit will easily strip the screw head. If the head of your screwdriver fits too loosely, find a bigger bit and file it down until it fits snugly before proceeding.

You do not necessarily have to follow steps 3-7 to remove the battery in order to replace the hard drive. However it is recommended to remove all power sources from electronics before working on them.

Remove the two exposed five-point Torx security screws along the top edge of the battery.

Use the tip of a spudger to bend back the finger of the "Warning: Do not remove the battery" sticker while you remove the five-point Torx security screw hidden underneath.

Lift the battery by its plastic pull tab and slide it away from the long edge of the upper case.

Do not try to completely remove the battery just yet.