Have you tried to reset the thermostat along with rebooting the touchscreen? You can see more info on troubleshooting for your thermostat: http://customer.comcast.com/help-and-support/home-control/thermostat-help/
If your thermostat is a complete digital thermostat, use this guide: http://customer.comcast.com/help-and-support/home-security/manage-xfinity-home-thermostat/