the power button on my hp printer scanner broke I didn't so much as fix it as make the actual power switch accessible.
Step 1: The Problem
in short the power button is badly designed and made out of rather brittle plastic. The part you press is over the illuminating led not the actual switch.
Step 2: The Solution
unfortunately I was in fix it mode not make an instructable mode so there aren't many photos. Prise the cover off with thin blade. The ribbon cable attaching circuit board with the switches on it to the internal electronics stops the cover coming off completely but you can twist it around so that you can undo the three screws securing the board to the cover. The remainder of the broken power button can then be removed from the cover and used to determine the centre point for the hole to access the power switch. This is approximately 6mm to the right of the edge of the button hole. I drilled a 2mm pilot hole and check the alignment. then opened it up to a size that would accept a stylus. The circuit board was then reattach to the cover and the cover snapped back into position. The power switch can now be operated using a stylus.
lf I wasn't being chased to get it working or we can buy a new one I could probably have repaired the broken button with cyno acrylate glue and some scrap plastic card.