I've updated it once, not to the latest image though, as people have been having some problems with that one.

Yesterday, the backlight went out again. I'm pretty much certain now that it is a hardware problem, as even rebooting would not fix it. I switched off the lights and in the dark I noticed that the screen is flickering slightly. Tapping the backside a few times brought the backlight on. I will probably send the 770 in for repairs.