My on/off button was not working and in order to replace this part, you must replace the ribbon cable to the on/off, headphone, mute and volume buttons.
The install was much more difficult then I anticipated mostly do to a lack of complete instruction. When you read the guide it tells you how to remove the ribbon. However, it does not mention the need to peel and apply the small adhesive strips that a located on the ribbon cable.
It is important to notice all of the self-adhesive location before reassembly, since they are required to get the components to stay in place.