Remote not remembering tv code - XFinity

Our remote, silver with white buttons, stopped being able to control the tv. I go through the programming/pairing and the tv can be controlled by the Xfinity remote. I can adjust volume and turn it off. When I turn the cable box and tv on again, the remote programming is gone, no tv volume. I've changed the batteries in the remote and tried all of the codes for Panasonic tvs and get the same results. Is there an internal battery that needs to be replaced and will that void any warranty on the remote? Will it lose all of its programming if I replace the internal battery?

This question, "Remote not remembering tv code," is about XFinity-Comcast TV television equipment.

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