Microsoft Windows

• Download Windows 11 ISO from Microsoft and write to USB.
• Boot into Windows setup utility.
• Select Repair computer -> Troubleshoot -> Advanced -> Cmd prompt

This procedure assumes the following:

• main disk is disk 0
• EFI partition is part 1
• Windows OS drive letter is c:

The following commands will format the old EFI partition, mount it to s:, and copy the boot files to it:

diskpart
> list disk
> sel disk 0
> list part
> sel part 1
> format fs=fat32 quick label=System
> list vol
> exit
mountvol S: /S
bcdboot c:\windows /s s: /f UEFI /v
exit