I've had the same issue with a manual. Try ensuring that the button isn't being depressed by the case.
The flickering seems to go on indefinitely. Not that I've let one flicker for very long. It does look like it would be jarring to the circuit and shorten the life of the battery. (By battery I mean the whole unit. When I say battery I only think of the power pack inside for some reason, maybe we need a new word to refer to the whole unit).
I've had them flicker on the USB charger too.
The flickering seems to go on indefinitely. Not that I've let one flicker for very long. It does look like it would be jarring to the circuit and shorten the life of the battery. (By battery I mean the whole unit. When I say battery I only think of the power pack inside for some reason, maybe we need a new word to refer to the whole unit).
I've had them flicker on the USB charger too.