Remote Power Down for Raspberry Pie 3 Model B+

This is a remote shutdown modification for the Raspberry PI 3 Model B+ that is using the stock Octoprint disk image. The circuit provides a ~25second time delay for the PI to boot and enable its external USB ports. Once booted, the power is locked in until the remote system shutdown is issued through the browser. Once the system shutdown starts, a approximate 25 second timer starts when the external USB ports are powered down. The 25 seconds allows the PI to fully park itself before removing all power. Starting the PI is always a push button cold boot and does not require recycling the power. This circuit can be modified with an additional relay to shutdown the printer power too which I will be doing on the next revision of this design. The implementation should work on other printers, but it was specifically done for the CR-10S which would have its display powered up when switched off if the pie was left in an operational state which is really annoying. (Updated circuit with miss