Safest way to block installation of system update after it's downloaded?

For reasons too long to go into, I have an unstable PC (thanks Lenovo) that will die (not restart) if it attempts to restart or powers down. While diagnosing this, I thought I had set all my Windows Updates to pause mode, but somehow a major update downloaded today and is prompting me to restart the system. If I restart, or if the PC restarts automatically, I'm pretty sure this will leave me with a dead computer and/or a corrupted update installation because the system cannot successfully boot in the state that it is in.

If the system does restart, for whatever reason, I'd like to make sure that the update that was downloaded today does not attempt to actually install. Is there a safe way to prevent that? I've found articles like the one linked below, that suggest that you can delete the downloaded update files from the Software Distribution folder, but I'm wondering how safe that is. I don't want to make things even worse than they are.


Thanks for any thoughts...

Seems like you should backup files that are important ASAP and get Windows reinstalled and booting properly.

You cannot expect to go a long time on a windows machine without a reboot. Typically you need to do it for security updates or simply as a troubleshooting step when it's acting up.

Simply trying to endlessly prevent a reboot seems a bit impractical.

You can't go on with a system as you described. Soon or latter it will restart.
As already suggested you should make a Data backup ASAP.
You can then try to do a Repair install . Download Win 11 iso, mount it and run setup. If you already have a Win 11 USB installation drive, run setup.
A better choice is to reinstall Win 11 (clean install).

You have just found out why making system images with programs such as Macrium Reflect is very important. If possible, download a backup program and save as much of your data as possible. You could try doing a repair install after backing up your data and see if that helps. If not, you may have to do a clean install and start over. Repair Install Windows 11 with an In-place Upgrade Tutorial

MS will override WU user settings for certain security updates and push them through. That said, may I ask why you do not update your computer? I can see someone stopping drivers from updating, but not the OS itself. It's definitely not a good practice.