Locate the reverse side of the buttons by looking at the inside of the back camera casing.

Locate the button sensors, which connect to the logic board by a connecting ribbon, by looking at the back of the camera once the back casing has been removed.

The button sensors on the back of the camera should appear to match up with the reverse side of the buttons on the inside of the back camera casing. Imagine one as being the reverse image, or mirror image, of the other. This will help you locate where a problem is occuring if a button or a button sensor has been damaged.