Boot err: File: \WINDOWS\system32\config\system Status: 0xc0000225

Debugging a Windows 10 system where windows were opening randomly and characters were being entered randomly, I put the system into Diagnostic boot mode then rebooted, and the fun began. Turns out PIN doesn't work in Diagnostic boot mode and the owner doesn't remember his login password. I was not smart enough to activate the built-in Administrator account before doing this (important lesson learned) so I've spent the last day trying to get the system out of Diagnostic boot mode.

After futzing with it (technical term) I used Macrium fix boot problems which would have put the machine back to normal boot, but now I'm getting a blue screen at boot:
The Operatting system couldn't be loaded because the system registry file is missing or
contains errors.

File: \WINDOWS\system32\config\system
Error code: 0xc0000225

I tried booting a install flash drive and opening a Command prompt and running (in case it was a BCD problem):
bootrec /scanos
bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd
When I tried to run bootrec /fixboot I get Access denied. How can I resolve this? Also, when I ran /scanos it reports

Total identified windows installations: 0

which is not right.

There are no backups other than the one I just created so I can't restore a good registry or import SYSTEM. Is my only fix to do a clean install then restore data from the backup I created yesterday?

Is there any way to run DISM from a booted install flash drive or from WIN10XPE?

As i remember, there is no registry backup where Windows no longer automatically backs up the system registry to the RegBack folder starting in Windows 10, version 1803.

Does the system have system restore points.

Please boot your computer with Windows Setup Media and from Windows Recovery Environment start the Command Prompt.

Please type below command into Command Prompt and press Enter key.

The following command scans integrity of all protected Windows system files and repairs files with problems when possible.

Code:

Sfc  /Scannow   /OFFBOOTDIR=C:\   /OFFWINDIR=C:\Windows

Please replace partition letter C: with Windows installed partition letter. When the computer boots into Windows Recovery Environment (WinRE) environment, the drive letter assign to Windows partition may not be C: drive letter because Windows 7, 8 , 8.1 and 10 creates a separate system partition when it's installed from scratch. The system partition contains boot files WinRE assigns the system partition the C: drive letter and the Windows installed partition will be assigned any other drive letter, usually D: drive letter is assign to Windows installed partition. The Bcdedit | find "osdevice" command can be used to find out the drive letter of the Windows installed partition, the output of the Bcdedit command is similar to this osdevice partition=D:. The drive letter after partition= is the drive letter of the Windows partition.

Also execute Chkdsk C: /r command.

Execute the following command from Command Prompt to delete NGC folder which will force PIN change on logon screen.

Rd /s /q C:\Windows\ServiceProfiles\LocalService\AppData\Local\Microsoft\NGC

@FreeBooter, no restore points. I was able to run sfc /scannow from a Command Prompt off of a booted Windows 10 install flash drive, didn't find or fix anything. I did find your post from a while back on how to run DISM from booted Windows 10 install flash drive though. Basically run this from the a Command Prompt once you get there (I elaborated a bit):

Create a junk folder in the root of the Windows boot drive (s/b C:)Copy and paste the following:

For Windows 10 Home:
dism /image:C:\ /cleanup-image /restorehealth /source:d:\sources\install.esd:1 /limitaccess /Scratchdir:C:\junk

For Windows 10 Pro:
dism /image:C:\ /cleanup-image /restorehealth /source:d:\sources\install.esd:6 /limitaccess /Scratchdir:C:\junk
@SIW2 Damn, I forgot all about shadow copies. I've used them before to recover from corrupted registry problems, just forgot all about them.

Too late now as I did a side by side new install and am in the process of copying all the customers data back from Windows.old. Got about 180GB but it's going will using robocopy.