I would think the first step would be to desolder one of the buttons and see if you can get to the traces on the board.
it is not very clear but if you can look at my 3rd attachment(IMG_20140404_175151), there you can see those plates that use to activate buttons are not even soldered so if i remove the sticker they would be removed.
so are you suggesting to finding the positive pin of the button and setting it as high in the arduino could work?
If i understand correctly let me try and come back here with the results.