Quick Take: Absolute Democracy

We all accept that, for the sake of liberty, undemocratic tyrannies must be overthrown; if not by peaceful resistance, then violent revolution. But what if there were a truly democratic tyranny - that existed by virtue of, and was accountable to, the mob? Would it then be justified to overthrow this despotic democracy, to defend liberty?

Supposing that Hitler hadn't abolished democracy, and was repeatedly reelected as Germany's Chancellor (which isn't an unlikely scenario considering his economic success). Surely righteous German citizens would still have a duty to oppose his genocidal regime regardless?

It seems to me representative democracy's true purpose is merely to ensure efficient, accountable government. It should never be permitted to evolve into a tyranny of the majority.