Which GPIO for shutdown switch?

I have a python script for my shutdown switch which allows me to shutdown the Pi3 via shorting the GPIO13 and ground. I did this a couple of times and now I cannot boot apm anymore, yet the Pi is doing just fine.

I swapped the Navio2 board for another one, and it runs, so I am assuming I fried the board. So the question is, which GPIO can I use, or was I just unlucky?

So did a bit more research, seems like my board is not fried and according to a forum post here, no GPIO pins are in use by Navio anyway.

My board works again and that is because the board and the extension header that is in between the RPi3 is far too loose.

Unfortunately it is the same for all my boards and it means I need to bend the pins on the connector ever so slightly so the Navio2 is making good contact.

I am rather disappointed with this because I did not have this issue on my Navio+. There, the extension header sat as solidly on the Navio+ as it does on the RPi.

Am I the only one, or does anybody else have this problem?

You have to fix the Navio2 with the provided screws and spacers. The connector is designed to have a low insertion force, but you have to fix the Navio2 to the RPi.

I did and that is still no where enough for a solid connection.