> M$ removed the "shut down cleanly" button from the language chooser

Not sure what language chooser you're talking about here, but if you're trying to shutdown Windows without hybrid shutdown to access the uefi, there's two switches you can use with shutdown.exe: `shutdown /s /t 0` will perform a full shutdown without hibernating the system session (not hybrid shutdown, that can be done with another parameter). If you want to reboot into your UEFI menu, use `shutdown /r /fw /t 0`

I may be confusing the time parameter, it might be `/t now` and not `/t 0`; I usually use a dedicated command to reboot to UEFI via slickrun.