If you turn off your windows computer while it is updating,
the files will be corrupted.
there is a possibility that it will not boot up directly to the windows.
In some cases,
it is feasible that it can be repaired by the Windows installer.
Other fortunate cases,
your windows computer will normally work even if you turn it off during an update.
That is as if nothing happened.
But generally speaking,
I would recommend you not to turn off your windows computer while it is updating because most often the system will malfunction the next time you turn it on.