I get this error: "Please Change Computer's Screen Resolution"

I changed the resolution on my Mac Mini, and apparently changed to an unsupported resolution for my display. The screen went totally black, except for this error message: "Please Change Computer's Screen Resolution"

Since I can't see the screen, I can't change the resolution (a Catch-22).

I can restart the computer, and it's fine all the way until I choose my account. I click my account, enter the password, and after a few seconds, it gives me this error, with the otherwise black screen.

I was able to boot into Safe Mode, and that let me use the computer (the monitor was fine), but when I went back to regular mode, same problem with the blank screen.

How can I get back to a supported resolution, without going to the Systems Preferences (and in general, without needing to see the monitor)? I