Simulating pad button press with GPIO rPI3
Need a relay:
I just did this for automatically opening my window blinds.  Clean off the +/- pads, then:
1) solder wires, 1 to each ground and voltage.
2) take voltage side wire and input to RELAY Common input port(screw).
3) take ground side wire and input to RELAY NO output port(screw).
4) wire up relay, Vcc=5V, Ground (pins).
5) Choose a GPIO output, wire to relay S1 input (through a 1K resistor). this is your trigger/switch.

When you toggle the GPIO, it will active/close the relay connecting each end of the pad switch. I had to create a 'pulse' for on/off, (turn it on, pause a few seconds, then turn if off) to simulate an actual button press.