If you are ever unable to boot into windows because of windows updates failing then try one of these two commands.
First get to the windows recovery tools for the OS and open the command prompt.
Try deleting the pending.xml file with this command
del C:\windows\winsxs\pending.xml
Then reboot the machine. If that doesn't work or the pending.xml file doesn't exist try this command
Then reboot again, and this time you should get a message along the lines of Failed to install updates, reverting changes. This message could stay on screen for a good 20mins but hopefully it should revert the updates and allow you to boot into windows again.