As I understand it, the thing is that Gear fit2 is only water resistant, and not water proof (unlike this model's successor, the pro variant). Now, I had similar problem which might have occurred either as a result of sweaty arms or the recent update. I recently purchased unoriginal band (with standard clasp, such as seen on this model's successor), and the connection (where band clicks into the watch) is not as snug as the original (sorry if English is somewhat bad, am a non native speaker), and thus the sweat might have found its way into the watch, and affected the altimeter sensor (with the exception of the stair counter, the watch worked normally). Even though the problem did occur only after i updated the software, I suspect it was the sweat (or moisture in general), because I've put the watch (with the band taken off) near my laptop's exhaust (vent opening), and had it there for some 10 to 15 minutes while playing an online shooter. When I was finished with the mission, the watch was warm and displayed message that it's going to shut down to cool down. I switched it back on when it cooled, and it counted stairs just like before the update and the new band. Ergo, I believe the rice thing might help (or putting it near moderate heat source for a shorter period of time - at your own risk). Hope this helps. Live long and prosper, and thanks for all the fish.