Windows 10 Hard disk won't boot. Files seem to be fine

One of my PCs just crashed after installing some drivers. First I got a couple of blue screens stating something like CRITICAL PROCESS ERROR.

After trying a couple of reboots, the PC wouldn't recognize the HD anymore.

Tried to boot from a Windows 10 USB but eventually it just said Your PC/Device needs to be repaired - Error code: 0xc0000098 file: /boot/bcd. Just an informational screen with no options.

So, I hooked the hard drive up to another PC by a sata to USB cable. The files are all there (and now are being backed up).

So, How can fix or restore the drive to be bootable again? I would like to this from the second PC, which is working fine and has the drive connected as an external USB drive. The second PC is running Windows 7. I have Administrator rights on it too.

I've seen various pages about booting from a CD or USB and doing a repair. I don't have a CD at the moment and for some reason the USB with a bootable Windows 10 doesn't give me those options.

You might try these directions for fixing the Master Boot Record:

The command in Windows 8/8.1/10 for fixing MBR is "bootsect.exe".

bootsect /nt60 drive_letter: /mbr

However, your statement "Tried to boot from a Windows 10 USB but eventually it just said Your PC/Device needs to be repaired," indicates there might be a more serious issue than just the boot record.

Check that the PC does not have other issues by booting from a stand-alone USB flash drive OS, such as Windows PE or Linux. If the PC cannot boot from a flash drive, you may have BIOS (UEFI) or hardware issues that need to be fixed before the OS can be repaired. Follow directions for setting up your particular BIOS to boot from USB: you may need to disable Fast Boot and/or Secure Boot, change boot order, and enable legacy (default) boot from USB.

You can get Windows PE from Microsoft, or create a bootable rescue drive with Macrium Reflect or similar tool... BTW, if you've imaged your HDD while it was healthy, restoring everything, including boot partition, is easy using Reflect or other imaging tool rescue disk.

Ubuntu 16.04 LTS can be run directly from the USB, or it can be installed by itself or with Windows on you HDD.