Upon receiving a call about a furnace that wouldn't turn on, I began by inspecting the thermostat settings and ensuring they were correctly configured. Next, I checked the power supply to the furnace and confirmed that it was receiving electricity. I then examined the furnace's control board for any error codes or signs of malfunction. After troubleshooting, I discovered a faulty igniter and replaced it, restoring the furnace's functionality. The homeowner was pleased with the quick and efficient resolution.