2002 Buick Lesabre electrical issues

I have two Buick Lesabres and unfortunately I have issues with both. My 2002 has various gauges that either randomly work or don't work at all. It happened all of the sudden while driving. Some dummy lights come on and off randomly. The fuel gauge and radio work sporadically- more often they don't work. The blinkers and tail lights don't work fully. The power locks and cigarette lighter have never worked since the problem occurred. There are additional things that happen randomly- blower motor stays on after key is removed, key left in the ignition dinging continues after car is shut off and key removed... I think you get the idea. I tried swapping out the body control module, but that didn't do anything. Also tried to get the car scanned but it the scanner gives a "can't make connection" reading.