Thermostat does not power on at all (blank screen, no lights)

Safety: You are working with high voltage. Turn off the suspected breaker before removing the thermostat. Use a non-contact tester to verify wires are de-energized before touching.

Steps to troubleshoot a dead Stelpro smart thermostat:

• 1. Check breaker and GFCI: Locate the breaker controlling the heating circuit and ensure it is ON. Reset any tripped GFCI devices in the circuit.
• 2. Test for voltage at wall box: With the thermostat removed and breaker ON, use a multimeter to measure voltage between line and neutral (or between two line legs for 240 V). You should see the rated voltage. If not, the issue is in the house wiring or breaker.
• 3. Inspect wire connections: Turn power OFF. Check that all wire nuts and terminal screws are tight and that no wires have pulled out of connectors behind the thermostat.
• 4. Check for damage: Inspect the thermostat backplate and main unit for burn marks, melted plastic, or a burnt smell, indicating internal failure.
• 5. Test with another device: If possible, temporarily connect a known-good Stelpro thermostat or a test lamp to the circuit to confirm power is present.
• 6. Replace thermostat: If power is present at the wall box but the Stelpro smart thermostat remains completely dead, its internal power supply is likely failed. Replace the thermostat.

Warning: If you are not comfortable measuring high voltage, hire a licensed electrician.