Hi Again
You have no choice after waiting for a very long period of time and you are certain that the updates will not load, you have no choice but to hold down the power button. This should not hurt the computer, but may corrupt the Operating System. Various problems are possible; not being able to boot or possibly losing some features etc.
To avoid the problem in the future, if you have many updates to install (set Windows Update to notify and not install) install only one or two at a time. Install the larger ones alone. In addition, you should make a back up of your Operating System in case of problems of this nature.