Surprised no one has chimed in yet. You'll want to get the computer into the Windows Recovery Environment (WinRE). Here's how Dell says to do it, but if you see any options regarding booting to safe mode or WinRE, you can try that too:
https://www.dell.com/support/kbdoc/en-us/000113309/how-to-access-the-windows-recovery-environment-in-windows-10From there, you can try the Startup Repair option, or do a System Restore. You can also try to Uninstall Updates, because it seems that's what broke something.
Or, you can try booting to safe mode, which will get you into Windows to try a myriad of things - uninstalling recent updates, System File Checker, etc. I'd start by looking for a recent update that coincides when it stopped booting, rolling that back, and then researching the update.