earlier this week. It got stuck at the close down screen where it says the updates were installing.

I took a chance. I powered my PC down by pressing the power button on the PC case for a few seconds.

Then held my breath, crossed my fingers and toes, and after 10 seconds or so, (to allow the hard drives to spin down), I turned it back on.

It completed the installation with no problem.

There is little else you can do at that stage. You can't halt the process or change it, and the only action is to power down and restart.