This is power ON & autoshutdown dispositive.
the scheme is very easy, there is tro pin for connect two relays. First relay control power on and off the printer and the second relay shutdown respberry when is connected.

There is one RGB led, this indicate the status of printer.
LED BLUE: printer in standby, push button for power on.
LED GREEN: priner power on mode, push button for power off printer.
LED RED BLINK: start 10 sec. timer for power off, in this time if you push power button the
led turn on GREEN and autoshutdown is reset.
LED RED: autoshutdown process is started and the printer shutdown after 10 sec.

To control the device, there is two inputs one for GND and other for digital PIN from printer motherboards.

To control digital PIN in start gcode put this string before all command
M42 M1 P(pin motherboard) S255 ;activate pin for autoshutdown

and in end gcode put this string after all command
M109 R50; Wait for the hotend to cool down to 50C
M42 M1 P(pin motherboard) S0 ;deactivate pin for autoshutdown

Download firmware from

https://github.com/rferrari81/power-ON-autoshutdown-for-3D-printer

and write on arduino