Win 10 Not Starting Up after Update

After doing latest updates of Win 10 where restart was prompted, laptop is not restarting/rebooting. Have gotten the black screen + circle which means 'loading' but nothing beyond that. Have waited 15-20 minutes, the mouse registers movement, but will not advance beyond that. have tried manual restarts by powerup several times and have same issue, cannot get laptop to start in scandisk. Cannot get to main login screen or bluescreen. Have attmepted manual restart at least 5 times and waited each time. Have left computer off for a period and then attempted to restart with no luck. Am unsure as to how to get it to restart to give any sort of access to prompts or ability to get alternate boot settings.

I am having the same problem with the 2018-05 Cumulative Update for Windows 10 Version 1803 for x64-based Systems (KB4103721). Have to do system restore to get it working again by booting from Recovery Disc.
Have tried the update 3 times today, but with the same result.
It now wants to reboot again to finish installing this update, but obviously, I do not want it to.
How do I stop it, please?
Many thanks.

Having the same issue on 2 PCs at company. Windows 10 hotline knows nothing about it. The qualification of employees is unbelievable.