Explorer pHAT exit triggering clean-shutdown

This is a fun one. I was playing with my Explorer pHAT and noticed that every time I Ctrl-C'd out of a script I'd get a message;

Broadcast message from root@raspberrypi (somewhere):

BCM 4 held low, system shutdown in 5 minutes


Broadcast message from root@raspberrypi:

The system is going down for power-off!


And yes, the pi would turn off. Every single time.

I don't know why the Explorer pHAT seems to pull BCM 4 low upon exit, when none of my other pHATs do. But I do know why that was triggering a shutdown.

I had also installed (though not in use) the Zero LiPo SHIM and the OnOff SHIM. They both install the clean-shutdown library that does just what it says, shuts down your pi when BCM 4 is held low.

It installs the cleanshutd service, but it didn't respond to my attempts to stop it, so I had to disable it.

In /boot/config.txt add;
disable_cleanshutd=1
Save, exit, reboot. Then you can play around with your Explorer pHAT in peace.