Pull out the bottom cover towards you and you will see three batteries...your thermostat should also be wired to power...if the thermostat is not working even with dead batteries, you should contact Comcast and tell them to wire it correctly for you otherwise you will be replacing batteries every few weeks.. Make sure that you install batteries in the correct directions!
Check these links: https://customer.comcast.com/help-and-support/home-security/manage-xfinity-home-thermostat
and
http://www.radiothermostat.com/documents/CT-30-Operation-19apr10.pdf
and
https://www.2gig.com/pdf/product-info/2GIG%2520ZWave%2520CT30e%2520Thermostat%2520Installation%2520Guide.pdf
Check these links: https://customer.comcast.com/help-and-support/home-security/manage-xfinity-home-thermostat
and
http://www.radiothermostat.com/documents/CT-30-Operation-19apr10.pdf
and
https://www.2gig.com/pdf/product-info/2GIG%2520ZWave%2520CT30e%2520Thermostat%2520Installation%2520Guide.pdf
