
Step 10
Place enough pressure on the upper case to allow you to slide a tool just within the seam between upper case and lower case as shown in the picture. A dentist's hook, push pin, or similar tool will work.
Do not yank the upper case off as soon as you free the clasp. The case is attached to the logic board via two ribbon cables.
Delicately slip the tip of your tool behind the silver metal latch and pull it forward while pulling up on the case. This may take some effort.

Step 11
Lift the back of the case up and work your fingers along the sides, freeing the case as you go. Once you have freed the sides, you may need to rock the case up and down to free the front of the upper case.
Rotate the upper case up and toward the screen, so that the upper case rests against it.





I was able to easily release the latch by putting the spudger in the optical drive slot, and gently prying up. You can see the three holes where the upper case clips in above the drive, and the clips are accessible through those holes from the optical drive slot.
"Forward" (step 10) means toward the front. I was not able to release the latch this way. However, I did eventually release all three latches at once by very slightly lifting the rear of the cover and pressing the cover back toward the screen.
It is not necessary to remove the trackpad and keyboard cables (steps 12, 13, and 14) to replace the hard drive.
I find it useful to use a big rubber band to hold the keyboard up--put it around the keyboard and display.