Inaccessible Boot Device Bluescreen after Security Update on Windows 10

When I turned off my PC yesterday, it seems that my Windows 10 installed a security update. But today, when turning on my PC, I'm getting Inaccessible Boot Device bluescreen. And no, I didn't install or uninstall anything new (no new hardware or software). It was simply the Windows Update that wrecked my system :(

All the following things I've already tried after googling:

• obviously Windows auto-fix boot feature didn't help


• I am unable to boot into Safe Mode --> also getting Inaccessible Boot Device bluescreen


• And chkdsk /f obviously also didn't find anything


• Booting with logging enabled didn't create the logfile at C:\Windows\ntbtlog.txt


• reverting to restore points from 2018-01-17 and 2018-01-12 didn't help --> same bluescreen


• successfully uninstalled the pending security update using the following command: dism /image:h: /remove-package /packagename:Package_for_RollupFix~31bf3856ad364e35~amd64~~15063.786.1.5 --> same bluescreen


• sfc /scannow didn't find any issues


• bootrec /fixmbr succeeds but didn't help


• bootrec /fixboot says "Element not found."


• bootrec /rebuildbcd does find my C:\Windows installation, but also fails with "Element not found." error


• bcdedit gives me the error: "The boot configuration data store could not be opened. The requested system device cannot be found."

Is there anything else I can try before resetting my PC? Is there anything else I can look into why my windows just doesn't want to boot?

My desktop PC:

• Intel i5-6600 CPU


• MSI Z170A-G45 Gaming (7977-002R) mainboard


• MSI nvidia GTX 970


• Windows 10 Pro Version 1703 (OS build 15063) (according to regedit hive)

why do I get "Element not found." error on bootrec command? And the weird part is, in diskpart I can see a 100 MB volume next to my Windows volume, but it has NTFS and it's partition type is Primary (not system or something). Shouldn't the EFI boot volume be in FAT32?

EDIT: according to windows install usb stick, my SSD formatted as MBR :o
Where and how can I verify that?

EDIT #2: just confirmed in partdisk. my SSD is partitioned with MBR.