Low voltage mistake

[amarlls]

Thermostat low voltage issue​

Hello please be gentle. I am sure this is a DIY/rookie mistake. So I am replacing some drywall and I planned to move my Nest thermostat to the next stud over for better access. I unhooked the 5 low voltage wires and pulled them out of that stud bay and moved to the next. I hooked it back up and now the Nest is saying that the red(power) wire does not have power so the nest will not work. What happened or what should I have done? I think maybe a mistake I made is I did not tape the open wires when I pulled them through the stud holes. Did I or was I not supposed to arc those wires together. I thought with low voltage it would not be aproblem? SHould I have turned off the power before I did this? It kicked an error on the nest that said (e74 Rc no power)

 

[Fitter30]

Need to look into the furnace or air handler for the transformer. Some are protected by a fuse on the control board, some might have a circuit breaker mounted right on it and some have a solder in fuse under the paper of the transformer made to just replace the transformer. Hopefully when the R to C probably touched and shorted out it didn't kill the board. Take a pic of the wiring diagram usually on the inside of blower door.

 

[Sponsor]

 

[Breplum]

many modern control boards have a little (usually purple) automotive fuse on board that can be pulled, tested for continuity (and visibly shows burnt).