Just went through everything and successfully replaced my power supply thanks to this excellent walk through. And it still doesn't work. Need to test the power supply, but probably it is the board itself that is dead? Sigh.

Thanks very much for this excellent guide. "Darker's" comment is a good one though - a method for testing the power supply would be great. I just returned from vacation to find my mini won't start at all and am assuming it is the power supply. Likely there is no way to test without total disassembly, but if anyone has a way it would be good to add here! Thanks again.