This afternoon I was installing a new rear view mirror with an integrated screen and wireless camera to monitor traffic behind my travel trailer. I was testing for a 12V source and heard a pop. Now shifter is locked, the heated seats, as well as the heater/AC, instrument panel lights are all not working, who knows what else. Any thoughts regarding what could have happened? Thanks much!

 

Wow, I feel for ya’.....have you looked at all of the fuses? Sounds like one or more of them let go in the interior fuse panel if the “POP” was that loud.

 

I believe SFUltimate gave you good advice.

So we can get a clearer picture of just what is going on,
What and how were you "Testing" for a 12 volt source ?
The recommended procedure is to use either a test light or a volt meter.
I believe we can probably guess what you heard and what you might have done. Some vehicles have a power distribution panel in the engine compartment along with a fuse panel inside the vehicle. If the short circuit you created was bad enough, it could blow a larger capacity fuse in the distribution panel along with a fuse in the interior panel.
If your vehicle has both , make sure to check them both. Let us know if we can be of any further assistance.

Your vehicle may have a network that could malfunction if things are installed altering the design of the network, worth checking out.
Your owner's manual will usually have a diagram of the fuse and relay panel(s) and what the fuses protect. That might help you choose where you might want to tap into for connecting a possible add on.

 

Vehicles use to be much simpler and easier to add circuits
Today there is so much tech that adding something could change the way the network sees the vehicle
Many things were added onto the BCM. Making it much more expensive if something fails.
The "testing" that created the "POP" ... must check all the fuses and fusible links.
Hopefully it is only a fuse.