Your motherboard probably has a header for a chassis intrusion switch, and presumably grub is open source, so you could probably do that with a few hours of hac

Your motherboard probably has a header for a chassis intrusion switch, and presumably grub is open source, so you could probably do that with a few hours of hacky coding. Or, you could use an Arduino Leonardo and simply emulate a keyboard that pushes the right sequence of keystrokes at the right time.