Success!! I finally fixed my Thinkpad.
I did something stupid then more and more stupid to fix it.
It runs Arch Linux with efistub booting. I messed with the EFI partition.
Then tried to restore the backup but got the trailing / thing wrong in the
cp command. Which I didn't realize at first. Instead I thought I needed to
recreate the EFI boot entry for Arch, so i deleted the old one.
I figured out that the efi partition had files in the wrong place. After putting that
right Windows would boot. Unfortunately I had already deleted the Arch
option.
I kept thinking the instruction had backticks and Arch would boot but not load
(blank screen) I thought I was messing up the partuuid in the command.
Now with the command using single quote it works!!!
Thomas