How do I troubleshoot a blank display on my Honeywell thermostat?

If the display is blank, first check the circuit breaker and reset if necessary. Make sure the power switch for the heating and cooling system is on and the furnace door is closed securely. Additionally, verify that fresh AA alkaline batteries are correctly installed in the thermostat, as these provide backup power. If the problem persists after checking all these items, contact Resideo Customer Care.