BSOD after Linux installation (?)

Currently experiencing INACESSIBLE BOOT DEVICE BSOD, there is some history

• sda is the 275GB SSD drive with only windows
• sdb is the 3TB HDD drive with only windows (in fact only a NTFS data drive, but with some application installed also, but not Windows)
• sdc is the 80GB SSD drive with only one Linux partition

Activities on this PC was done in the last two weeks as experiments in preparation for a new PC whose components arrived just this Friday. The new PC will have new components but also cannibalize some from the old one

- New CPU, mobo, ram, case
- new ultra wide screen display
- new SSD for Linux (different from current sdc used only for testing)
- new GPU from Nvidia to be used only for compute
- old sda, sdb maintaining current Win10 installation and data
- old GPU from AMD to be used to drive the display

Being dedicated to data science prototyping (not development, the goal is just testing and understanding new tools to promote new projects) he will have Linux boot on one (new) disk and Win on the old one to maintain some projects.

These the activities performed on current old PC

1. The original PC configuration was sda + sdb with only Win10, perfectly working
2. Changed GPU from AMD to Nvidia, cleaning drivers before using Display Driver Uninstaller. Win10 perfectly working after reboot.
3. Tried booting from Linux live USB, failed to do that I tried to install Grub2Win to try booting from a Linux iso file I loaded on sda. I was never able to boot from this, even if Grub2Win attempted to do it and in fact generated a swap and other files on sda. There was a lot of forced shutdown in this situation when I remained stuck, in theory no OS was anyway loaded. Win10 installation tested and still correctly working.
4. discovered I can actually boot from USB (my fault creating the USB disk using Rufus), so started testing various linux distro using live USB so no change on PC. Win10 working. Didn't removed Grub2Win nor the Linux iso and related files from sda (maybe a fault)
5. Added sdc to the system (an old SSD I was not using) and installed there Kubuntu. From there I tested only using Kubuntu and never entered again on Win10.
6. Arrived and installed new ultra wide screen display (previous testing on FullHD TV), working on Kubuntu. Noticed the startup time was getting longer with the multiple steps I was telling at the beginning

And here we are. Current situation is visible here from the Boot-Repair report.

A single time actually Win10 started in a regular way, just after a lot of time working on the Win boot screen. I didn't changed anything in the configuration to achieve that. Updated some display drivers, rebooted and now again Win10 didn't start, with error message INACESSIBLE BOOT DEVICE.

I can also access windows boot disk using Kubuntu Dolphin so the file system is intact.

What I tried

1. Tried to use Boot-Repair Linux utility, without any success.
2. Tried also to remove Nvidia card and switch back to AMD one, no success either
3. Tried removing sdc with Kubuntu installation and the system didn't boot at all and reach only a grub screen with no option and a grub command line.
4. Tried to enter in safe-mode, no success.
5. Tried using other options for autorepair, siwitch back toprevious release etc didn't work no action is possible

I'm stuck and did't know how to proceed, any suggestion is welcome.

Just an update, using Boot-Repair I flagged sda as bootable and I was able again to boot Windows.
Not sure this was the problems since in my understanding there was also some Windows update going, but so far, back to normality.