Razer Recovery does nothing, Error Code 5

Hi there,

I've tried to restore my Razer Blade Pro (2020) completely to Factory Defaults.
I really want to keep the pre installed Razer OEM Stuff, so I choosed to use the provided Recovery Partition (F9 on Boot) and not the Windows Clean-Image-Download-Restore method.
After a short loading screen the Razer Recovery showed up and asked me if I really want to restore the System Drive to Factory Defaults.
At this point all my personal files are copied to an external drive.

I choosed "Yes", than a Message-Box appeared with the Content "5", no Text in the Titlebar, no Warning or Error sign, just 5 and a Button with "OK".

I choosed "OK" and surprisingly fast it said "Restore successful" and the Laptop had shut down.
After reboot everything was the same, my User Profile with all my Settings, Files and Programs were still there.

Was does the "5" mean?
How can I fix this?
The Recovery Partition is present, untouched and uses about 16 GB beside Partition C:\\

What I'd already tried:
- In UEFI I've loaded optimized default settings, saved and exited, same result (5)
- I found an option to trigger the Reset from Razer Synapse, which didn't even perform a restart, no Errors in any Log Files found
- I started the Razer Recovery Mode from Windows' "Shift + Restart" Menu, same result (5)

Maybe it's worth noting, that I've installed an additional 1 TB SSD and replaced the RAM with 64 GB, everything is perfectly working, but I messed up some of the Windows installation, System Files, Drivers, maybe Viruses and want to start fresh.

Please help.