G3/4 Shows "Input not supported" after res change, how to change back?

I have an old G3 or 4 running 9.2.1, I just use it for one program, I boot it up about once a month, when it came up last time the resolution was all off, I went in to the monitor settings and changed it back to what I thought it should be, now all I have is a black screen with a blue box saying "Input not supported" and no apparent way to change it back. I booted it in safe mode but it won't let me open the monitor control panel because the extensions are off - UGH!

This is crazy, HELP?

There must be some way to start this up and reset it

Thanks