No power at key, just one click?

Battery is good (fully charged), new starter and solenoid (just replaced-not rebuilt), I naturally thought it was a bad solenoid. It was running fine, until I installed a new electric fan. I was connecting the wiring and couldn't get power to fan when getting hot. So was checking the fan with my power probe and it worked but after running the fan with power probe for 10 seconds. Lost all power to key. Can't roll the windows up (power windows) lost all power to everything. I have checked every fuse. They are all good. Please help, I am dumbfounded.