changing boot method one way to stop PC booting completely.
This indicates that a critical system process died. A critical process is one that forces the system to bug check if it terminates. This can happen when the state of the process is corrupted or otherwise is damaged. When this happens, as these processes are critical to the operation of Windows, a system bug check occurs as the operating system integrity is in question.
Built in Windows critical system services include csrss.exe, wininit.exe, logonui.exe, smss.exe, services.exe, conhost.exe, and winlogon.exe.
https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/bug-check-0xef--critical-process-died
not sure why you would get that error from just changing EUFI boot method,
Intel Serial I/O, and hotplug. None of the exe files are boot files.
csrss = client services (your user)
winnit.exe = windows initialisation (refer boot)
logonUI - Logon UI (pretty obvious)
smss.exe = Session Manager Sub System.This program is important for the stable and secure running of your computer and should not be terminated.
Services.exe = PC won't work without it
conhost.exe - The conhost.exe process sitting in the middle between CSRSS and cmd.exe allows Windows 7 to fix both of the problems in previous versions of Windows—not only do the scrollbars draw correctly, but you can actually drag and drop a file from Explorer straight into the command prompt:"
Winlogin.exe - This process performs a variety of critical tasks related to the Windows sign-in process. https://www.howtogeek.com/322411/what-is-windows-logon-application-winlogon.exe-and-why-is-it-running-on-my-pc/
its likely the error happened before windows had a chance to create a dump file, there are a few times that can happen. Not being able to login is one of them.
Perhaps you should make the changes before installing Win 10. UEFI should be boot method on Win 10 PC anyway.