New
#11
Dorian, before you do anything else, do you have a backup in case of things going wrong? Also, it would be a good idea to have a copy of Version 1803 (Build 17134.xx) on a bootable USB stick to reinstall, again, if things go terribly wrong.
Go to heidoc.net and download their Microsoft Office and Windows Download Tool and run it.
FYI: This tool allows an easy and comfortable way to download genuine Windows 7, Windows 8.1 and Windows 10 disk images (ISO) directly from Microsoft's servers, as well as Office 2010, Office 2013, Office 2016, and Office for Mac.
I haven't been there for awhile, so I don't remember the instructions, but it's pretty easy to understand how it goes.