Despite in both During Activity and General Use, Keys, Alerts and Gesture are all set to off. The problem is that, during daylight, I can't see the backlight anyway so it just burns battery since I have a long timeout. Seems to be a bug.
Known by Garmin? Sometimes we get a Garmin rep to work on a problem reported in this forum but sometimes not. This problem was identified very early on but not addressed in latest FW. Seems like it should be an easy fix.