In the process of installing a new stereo speedometer not working

I'm in the process of installing a new stereo and can't get it to work. On top of this, now my speedometer is malfunctioning, my odometer, tripometer, dome lights, window and lock controls don't work. Plus my bright lights indicator stays on and turns off when I actually turn on the brights. Any help would be greatly appreciated. This is not my first stereo install, but with that said, it is possible I accidentally had wires crossed. But I did have the negative terminal disconnected during install.