Hi, I have a Totaline P374-1000 thermostat. The screen went blank so I replaced it with a brand new one. I actually have two units one upstairs and one downstairs (the upstairs one was blank). After replacing upstairs unit screen was still blank, all breakers have been checked and reset. The bottom one was working fine so I checked both upstairs and downstairs for voltage and got 24V on both. I just put the unit back onto the wall plate donwstairs after confiming voltage and now the downstairs display is blank as well.

Please help.

These units do not have batteries and the downstairs one was working fine until I checked the voltage

Steve

The sub base may have shorted from a faulty stat(upstairs) and when you put the faulty stat on the good sub base (downstairs) you shorted it as well. When replacing the stats make sure you replace sub base and all.