just had to replace batteries in one of my XFINITY Home thermostats, and this procedure, previously posted, still works 100%. The procedure stated in the Comcast link regarding replacing batteries DOES NOT work...follow mine!
AFTER installing new batteries (behind bottom cover, which slides forward):
1. Power off Comcast modem, then power back on,
2. Power off Xfinity Home router, then power back on,
3. Once bothe the modem and router are functioning again, reset the thermostat (button behind top cover which slides forward). This resets then shuts thermostat off, then turns it back on. Check your thermostat settings, and your good to go!
Beeps every few hours finally stopped (if you are unfortunate to get these beeper I wasn't, and ALERT message on ipad and touchscreen FINALLY went away...hopefully for good, or until the batteries go again!
GOOD LUCK...PM me if you have any issues...