A brain is a terrible thing to waste!
First off, have you even tried what suggestions were given you?
Secondly, you might have experience installing wires, but obviously not trouble shooting. Two entirely different animals.
Common sense is an oxymoron, if it's so common, why do so few possess it?
You were given EXAMPLES and SUGGESTIONS on how to address you problem. I know exactly what you are saying and what the problem is. But you've got to physically get dirty, wedge your hand into impossible spots blindly and incredibly fix an unfixable problem. Want specifics? Ok...
Id pull the carpet and find the spot where you stick the screwdriver and make things work, obviously this is where a wire is shorting or cut. Yes, you will have to take things apart, including maybe your dash, the vents, the blower fan, etc. I would then go underneath the vehicle and have someone move the harness that is shorted so I can see it coming through the firewall via movement... Then I would OPEN the harness up on both sides and start pulling each wire trying to see if it or they are broken, if it is, it will pull out of the firewall. Easy fix from that point forward. Otherwise, it's a short and harder to find. If its a short, with wiring diagram in hand, I would identify the wires for the circuits you mention are effected. I would just cut those, replace the wires from engine bay to the underside of the dashboard. I would en test everything prior to reassembly and make sure my beers are on ice for a victory celebration!
Otherwise, just deal with it or sell the car.
Happy Trails!