How do I force Windows updates to install?

Have you tried re-downloading the updates? I noticed Windows 10 sometimes got stuck in the process of downloading or installing updates.

To do this, you need to completely remove all the downloaded update files.

• First of all, you need to temporarily disable the Windows Update service (Go to Control Panel - Administrative Tools - Services, then look for "Windows Update", right click - properties, Stop service, and just put it to Disabled on startup type, just to make sure)
• Now you need to find the location of the downloaded update files, which is in C:\Windows\Software Distribution\ folder.
• Delete the entire content of the folder (or, if you want to be secure, back it up first somewhere else). This will delete all the downloaded update files and windows update history. Don't worry, this WON'T delete your installed updates.
• Now that you've deleted it, turn the Windows Update service back
• At least reboot your Windows once, before trying the update process again.

This method has worked twice on my Windows 10 Home, when it got stuck in downloading and installing the updates.

I hope it works, and cheers.

Did you try creating a 1511 update install ISO? You can boot them to do fresh installs, but I also used mine to install 1511 without using Windows Update.

You can download the media creation tool from https://www.microsoft.com/en-gb/software-download/windows10