I recently installed this nest to replace my old thermostat - it was not a smart thermostat and it was operating without any batteries (forgot to insert them). I installed the nest, hooked up the wires as it was before to the old thermostat and then when I ran the system it wasn’t powering on. I inspected the furnace and saw the fuse had popped. I reconnected everything, ran it again and had the same issue. I noticed there was one blue wire not connected, and another blue wire connected to”C” along with a bunch of other wires on it as well. Not sure if this is wired correctly but I suspect something here is causing the issue.
when I relocated the blue wire to another slot the fuse didn’t pop but naturally it was not recognized on the nest and it was running on battery power only. But other than that everything else worked fine.
