Okay y'all, I'm baffled.
I went to try @chronosJ's suggestion and had the thought to completely unplug the turned-off machine for 10 seconds before trying to troubleshoot. The display is back now. I'm more confused than anything.
Anyone have any thoughts on why that fixed it? I powered the machine off/on probably ~10 times trying things before I posted here, so the only difference was that the machine had no power for a bit.