try opening it up and taking a look at the buttons.
the buttons are a different design to the pads since they're just buttons.
what you'll find is that the buttons are just bits of plastic that flex when you press them so pressing them pushes a lower part of the button onto the actual button underneath that triggers the function.
the plastic sometimes gets bent out of shape, which is why i had a panic attack when my F4 button got messed up after i didnt pack it so well in my bag. but i foundthat the plastic button thingy was just a little bent, and all you have to do is twist it back into place.
if its the trigger thing under thebutton thats not working then i'm afraid i cant help you out there. you might need to get that replaced, but it looks like something an electrical engineering student could fix. might even come up with a better thing.
