Actually, I occasionally have an issue where I plug the charger in (which activates the screen), turn the screen off with the slide-switch, yet the yellow flashing LED doesn't come on. Instead, the LED pulses with an extremely dim reddish color, barely visible unless you look at it in darkness.

I unplug the charger, wait 30 secs, try again, and it works normally - yellow pulsing LED indicates that it's charging.

I presume it's some weird edge-case not being trapped in software...