To manually set up your Nest Thermostat E, follow these steps: Turn off the power: Switch off the power to your heating and cooling system to avoid any electrical issues. Remove the old thermostat: Carefully remove your old thermostat and take a picture of the wiring for reference. Label the wires: Identify and label the wires connected to your old thermostat. Connect the wires to the Nest base: Attach the labeled wires to the corresponding terminals on the Nest base. Attach the Nest display: Snap the Nest display onto the base and turn the power back on. Follow the on-screen setup instructions: The thermostat will guide you through the setup process, including connecting to Wi-Fi and setting your preferences.