A couple of hours after I finished a ride, I happened to look at the 840 and saw it was still showing the circle with a line through the top of it that you get when you power it down. It usually goes away after a few seconds, but this time it was still showing after a couple of hours. I had to hold the power button 10+ seconds to get the 840 to reboot and then power down normally. On rare occasions in the past, I tried to turn on the 840 beforer a ride only to find it was dead and needed to be recharged. In those instances I thought maybe I had hadn't turned it off after the previous ride, though I didn't think that was likely....but maybe. This time, I caught it in the act of not properly shutting down.