Using TTP223 Jog Capacitive Touch Switch, a startup/shutdown button can be mounted on Raspberry Pi 3. Using jumpers, connect GPIO pins 5 and 6 to the ports indicated in the image below. The red wire (3V power) to Pin 1 or to Pin 17. If Pins 5 and 6 (Ground) are tight because of some other connections, the alternative is put ground to either Port 9 or 14.