I got it figured out. I'm really not quite sure what happened, I tried that several times using the Windows M5Burner tool and it didn't work, but the Linux one did the trick on the first try.

So I flashed the NES emulator to see what it was all about, and now that I'm done with that I want to go back to the original firmware... But... The M5 Burner program is no longer able to flash my M5Stack. I assume there has to be some way to do this, probably with esptool, but I haven't been able to figure out how to accomplish this. Can anyone point me in the right direction?

Thanks!