It seems that i cannot open the bottom cover after getting all the screws off, anyone know why?
My 2010 17" has two small snaps underneath the center of the cover.
Pry carefully and as straight up as you can and the cover will come off.
When you replace the cover, position it correctly, and push down where the snaps are to snap the cover back into place, then replace screws.
I just swapped my HD out. The lid is on fairly tightly and it does feel like you missed a screw but if you took out all the screws on the bottom you didn't. Just gently and slowly take your finger around the edges prying it up as you go. It will pop out w/o damage.
Any problems...beachballing etc...???