To crack open the 2nd generation Apple TV, you'll first need to remove the case's rubberized base. I used several thin, metal spudgers to pop the base free from the shinny black case. The base is held in place with plastic tabs. It may take a few minutes, but you should be able to pop the tabs free without breaking them.
Photo by: Bill Detwiler / TechRepublic
Caption by: Bill Detwiler