here is a few pictures of a motherboard with four tactile buttons. (old mobile phone) which you can replace your old buttons on your key fob.  the yellow lines point out the four contact pins which you heat up with a soldering iron one by one, the green lines is where you place a very fine sewing needle and lift up when heating up each pin. ( the blue line is the button.)  no solder is needed as you use the existing solder when heating up the four contact pins.  you can also buy these tactile bu