How do I log into my MacBook Pro when I shut it down after an update froze and wouldn’t go anywhere?

Okay, so I got a notification today on my MacBook Pro where I needed an update for a dark theme and a system update. So I clicked on it and made sure my Internet browser was closed and as well as other things I had opened were closed and then it restarted like it always does when it has an update. Now, as it’s updating, I’m now doing some other things I have to do before I go to bed while it updates. I look back after sometime and it says it has 53 minutes left to finish the update, and thought all was well. I come back about 10 minutes later and it says the same thing. Thought that was odd, but I went back doing what I was doing prior to checking the update. So I come back 10 minutes later, now around 20 minutes since the restart and update began, it is still 53 minutes away from the update completing. So, I did what I had done a couple times before when updates like this stall and won’t continue. I shutdown the laptop , turn it back on, and I went to login. However, unlike the few times before when this happened where I logged in and went back to do the update over again and it worked, this time I just get the login bar being from about a third of the way from being complete to going to a black screen, restarting again, and then telling me my computer restarted because of a problem and to wait or press a key to continue starting up. This is quite annoying as this hasn’t happened before. And before anyone says it, I know it probably wasn’t good that I shut the computer down when it was updating, but again, I had done that a couple times before when such an occurrence happened and I was able to login and restart whatever update I had no problem. So, now what do I do? How do I log into my computer so I can update it?