The first thing I'd suggest is seeing if a hard shutdown (hold the power button down until the machine shuts off), done three times in succession, will get the Windows 10 recovery environment to come up. If it does you could try the repair option.
If that does not work, then before continuing I would extract your hard drive and make a backup of all of your user data. If you already keep backups on a regular basis then doing this will not be necessary.
Next, if you were not already on Version 1709, I would consider following the instructions to Updating Windows 10 using the Windows 10 ISO file but with changing the early steps to boot from the media you create, since the machine you've got on your hands is not booting up fully.
If that doesn't work then it's time for a clean install of Windows 10 using the media you created and used to attempt the upgrade.
Brian AKA Bri the Tech Guy (website in my user profile) - Windows 10 Home, 64-Bit, Version 1803, Build 17134
Memory is a crazy woman that hoards rags and throws away food.
~ Austin O'Malley