There's nothing to stop the motor from driving the window right on through the frame, other than the limited amount of torque a small motor can make....
Yes, you are going to damage things, or already have, by keeping your finger on the button. Chances are also that something in the regulator has moved or bent some so that the window isn't aligned right or is not quite able to get all the way up before the gear segment runs out of teeth.
It's unfortunately going to need a replacement and if you're REAL LUCKY you might find a junkyard replacement regulator that still works.
The aftermarket replacement units are costly.
Good luck and go easy on it!
You can open up the door and see if any of the 10mm bolts are loose or appear to have moved around recently.
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Rob Bareiss, New London, CT 86 244, 87 244, 88 744