If your thermostat is blank, the first thing to do is to test to see if voltage is present at the rear of the thermostat. If no power is reaching the thermostat, please inspect the circuit breaker powering the thermostat in the breaker panel, and verify that the breaker is a non-GFCI type. If it is a GFCI breaker, replace it with a non-GFCI breaker. If there is power entering the thermostat and it is blank, it will need to be replaced.