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.
Both Aimpoint and Eotech are popular reflex optics for the AR15 family of weapons. Constantly online and there are heated debates over which is the better optic and many people have differing opinions for different reasons. There is one major reason the Aimpoint should be picked over the Eotech for home defense. This is the Aimpoints battery life and run time. An Eotech needs to be turn on before use, and will run 4 or 8 hours before shutting down. The Aimpoint will run months to years depending on model and brightness.
The Soldier or the police officer when going on duty or starting a patrol has the time to turn on an Eotech. You don’t know when you might need to use a home defense rifle, and you shouldn’t want to have to turn on its optic before you can use it. Even worse would be if your battery is dead when you need it. The new Eotech EXPS3 has a listed battery life of 25 days on setting 12. The new $400 dollar Aimpoint PRO will run 3 years on 3/4 max brightness.
Back when I owned an Eotech 512, I often found the batteries were dead when I wanted to use it. I had to store the batteries out of the optic to keep them from draining. Not only did I have to turn it on before I would shoot, I would have to check during the day that it is still on. When working at the range, I have seen more then a few shooters day at the range ruined when the only rifle they bought has an Eotech with dead batteries and no iron sights.
If your rifle is a fun gun, get the optic you prefer. But if you require a reflex sight that is ready all the time, use an Aimpoint.