Mine made a loud knock and then just stayed down after trying to bring it back up a few times. The window, from what I can see inside of the door, is stuck against what looks like a grinding stone. Taking it to the mechanic tomorrow and I have to retint the passenger window. I'll see what my mechanic says. However, my issue started because of the rain guard visor I installed. It was hitting the door whenever I would open it too fast; not giving it enough time to come down that one inch when you pull on the door handle. Looks like I through something out of alignment.