If you have lost your Sensi Security code, used as your Sensi's Wi-Fi password during Wi-Fi configuration, you can always find it on a sticker on the back of the thermostat in the upper left corner.

If you grab the top and bottom of the device and pull straight out the main part of the device should come out easily, and as long as you have batteries in the device, it will continue to stay powered on to allow for Wi-Fi configuration.