Windows 10 Installation Media:

1. Insert the Media (DVD/USB) in your PC and restart.
2. Boot from the media.
3. Select Repair Your Computer.

Select Troubleshoot.

1. Choose Command Prompt from the menu:

Type in the command:

Diskpart

Type in the command:

List disk            (Note which disk is your Boot drive number mine is 0)

Type in the command:

Sel disk 0

Type in the command:

List vol               (Note which volume is the EFI partition mine is 4)

Type in the command:

Sel vol 4

Type in the command:

assign letter=V:

Type in the command:

Exit

Type in the command:

V:

After you have assigned a drive letter Using Diskpart You can format the EFI partition:

Example: if you assigned a letter V to the partition the command would be:

format V: /FS:FAT32

After the format you need to recreate the EFI directory structure with the command:

MD \EFI\Microsoft\Boot

Then change to the Boot directory with:

cd /d V:\EFI\Microsoft\Boot\

Then run:

bootrec /FixBoot

Finally run:

bcdboot c:\Windows /l en-us /s V: /f All

Type in the command:

bcdboot C:\windows /s V: /f UEFI      (This replaces the above crossed out lines and works in Win 10 1709)