I tried to switch to a new smart thermostat in my home. When I was adding it, something happened. The new thermostat didn't show any power (And yes, the C wire was plugged in). Not knowing what else to do, I tried to back out and put in the old system, but I'm still having the same issue of nothing seeming to work. To try and diagnose things further, I turned off the power via the fuse box, and measured the resistance between each of the 5 sets of wires. I noticed that the R, C, and Y all appear to be shorted to each other, while the G and W wires appear to not be connected to anything. I know that there is AC power magic, so a DC short doesn't necessarily mean anything, but I am somewhat worried that the C and R appear to be shorted to each other.
Also of some note is I can't detect any AC voltage between C and R, even when everything is powered on
Bottom line, does this mean I broke something, and if so, what do I need to replace? My suspicion is that I blew out a transformer that will need to be replaced, but I would like to confirm this if possible. Thanks!