Rebuild EFI

Commands

sudo su

fdisk -l

## sda - EXTERNAL ##
mount /dev/sda2 /mnt
mount /dev/sda1 /mnt/boot/efi

## nvme1n1 - DESKTOP ##
mount /dev/nvme1n1p2 /mnt
mount /dev/nvme1n1p1 /mnt/boot/efi

## nvme0n1 - Laptop ##
mount /dev/nvme0n1p3 /mnt
mount /dev/nvme0n1p1 /mnt/boot/efi

for i in /dev /dev/pts /proc /sys /sys/firmware/efi/efivars /run /etc/resolv.conf; do sudo mount -B $i /mnt$i; done
#modprobe efivars
chroot /mnt

## Install Grub Package ##
apt-get install --reinstall grub-efi

## sda - EXTERNAL ##
grub-install /dev/sda
grub-install --recheck /dev/sda

## nvme1n1 - DESKTOP ##
grub-install /dev/nvme1n1
grub-install --recheck /dev/nvme1n1

## nvme0n1 - Laptop ##
grub-install /dev/nvme0n1
grub-install --recheck /dev/nvme0n1

update-grub

## Verify EFI ##
efibootmgr -v

exit
reboot