Dell Win 10 MBR Inaccessible boot device

Symptom:  Post Windows Update MBR based Windows 10 installation fails to locate the Windows partition.

bootrec /scanos returns, total identified windows installation 0

Note:  boot rec is returning the number of 'new' windows installations not already in the BCD store.

Identify that the boot partition is present and active with diskpart

select disk 0
list part
select part
detail partition

The current BCD configuration is shown with

bcdedit /enum ACTIVE

Resolution

1. Boot to the recovery environment using the Advanced boot options menu or by booting from Windows install media

2. Unhide and rename the BCD store

X:>
C:
attrib -r -s -h c:/Boot
ren Boot Boot.old
bootrec /rebuildbcd

3. Restart.  Windows may fail to boot.
Enter the advanced boot options menu and restart in safe mode

Additional: bootrec /fixmbr - writes a Windows compatible MBR without over-writing the partition table.