This thread hasn't been touched in a year, I see, but I wanted to let you all know that the Crestron TPMC-10 started life as a Viewsonic Airsync V210 tablet. This may help you in your search for a replacement battery. I am currently on the search for one for a client and it has proven to be a challenge. Just 6 months ago I could find them in several places but having trouble finding one source online at the moment.