When I turned on my SP3 at the beginning of class this morning I realized that things were amiss. My Type Cover had stopped working completely, and the screen autorotation was broken with the orientation permanently locked in portrait mode. After freaking out, impulsively doing a factory restore back to Windows 8.1, and freaking out more because the restore did absolutely nothing, I was about ready to resign myself to a fate of dealing with Microsoft customer support and getting a replacement. Of all the times to crap out...my Surface just had to choose the week before Block 1 final exams. At least the damn thing was still under warranty.
It turned out that all of the freaking-out was unnecessary. After speaking with Microsoft's Surface tech support over the phone (they're awesome, by the way), apparently all that was needed was a dose of the infamous two-button shutdown. After reinstalling Windows 10 Pro and Office 2016, all seems to be well again in Surfaceland.