Okay, this one has me stumped. On my SP3, the two-button shutdown process worked as expected--hold power + volume up for long enough, the system shut completely down and I could then restart. On my SP4, however, when I do power + volume up, the UEFI settings screen comes up. I can't seem to get it to shut all the way down. Anybody else see this, and have a way to perform the full shutdown?