Click Wheel vs Hold Switch

I am trying to resurrect a 5th Generation 60GB Video iPod. It has been dead for quite some time and I thought it might be the battery so I have replaced the battery but still nothing comes on. I saw where people were needing to replace the click wheel but I am not sure why they are doing it so I broke down the ipad to get to the click wheel and I have noticed something that I am not sure is relevant or not. With the click wheel removed you can see the the 4 outside button (Left, Up, Right, Down) and when you push them they click. The center button does not click when pressed. Is this normal or is this an bad button? Should it click like the other 4 buttons?

I also remember when the ipod was working that I could never really get it to turn off. I assumed that is what wore down the battery and that by replacing the thing would jump back to life. Could it be possible that I received a bad battery? Is there a way to test it? When I reassembled and plugged it in to charge, nothing came up on the screen. I even went back in and checked all the connections. Could it be the logic board is bad? Is it something to do with the hold button up top?