I bought this used Aimpoint T-1, the former owner managed to turn the adjustment knob past the stops.
In this particular case, the optic works fine unless you rotate it past its limits. If rotated past the limits it stops working until its turned another whole turn.
It is kind of rare to hear about broken or damaged Aimpoints, but if you abuse them, it can happen. In this case the aftermarket battery cap had been cross threaded on and the optic was most likely damaged when it was forced off.