The home button works by making contact with 2 pins on the dock connector flex. You can see them around where the home button flex metal pads are suppose to land when the screen is closed. On the dock flex side, they look like 2 metal pins that stick out. If you actually bridge them, the home button activates. With the phone on, try bridging it with a paperclip or knife, it should activate the home button. If it doesn't, it's probably a bad dock flex. If it does work, it just might be that the home button flex is not making contact with the dock side. Could also be that the home button flex was damaged.