I got the PSU mostly installed, but I had the wires on the screen crossed when I installed it, and I think I might have fried something. I guess I should have checked the output with a voltmeter first. Everything is straight now, but I need to take the screen out and see if I can see something that is smoked.
I ended up just getting a DPST (even though it said DPDT) switch so that it's just normal or valet mode.
Still more work, but I had to come inside and take a break, I'll hopefully get the screen out and diagnosed tomorrow. (BTW, still waiting on the touch panel...)