I messed up my EFI boot

I have Debian installed on /dev/sda4 and it’s using EFI. I installed Arch Linux to another partition, /dev/sda5 the other day and it created a new GRUB2 menu during boot. Unfortunately, I somehow messed up the installation and when I chose to boot Arch from GRUB2, I get an error:

error: no such device: d4103fa-d940-47ca-...
Loading Linux core repo kernel...
error: no such partition.
Loading initial ramdisk...
unaligned pointer 0x22
Aborted. Press any key to exit.

Once I pressed any key, the Debian GRUB2 menu was displayed (giving me the idea that 2 GRUB2 menus have been installed to the EFI boot partition) and I was able to boot into Debian.

Since Arch didn’t want to start, I reformatted /dev/sda5 to remove it and went to remove it from the EFI boot parition. I searched the web on how to do this and came across this post which basically says that GRUB2 isn’t needed to boot Linux in EFI; EFI stub can be used. Thinking it would work, I reformatted /dev/sda1, where my EFI boot partition is, and followed the instructions.

Reboot…computer is stuck with a black screen with a blinking cursor on the top-left corner. Not a good sign. Waited a full 5 minutes to see if it would boot up. Nothing. Rebooted 10 times more. Nothing.

I knew I messed up my EFI boot.

After doing a lot of reading, I felt that it would take too much time (4chan was waiting…LOLs) to get my boot loader back up without GRUB2. So I decided to reinstall GRUB2 via a chroot environment using Mint 16 live USB (booted in UEFI).

Inside Mint, opened a Terminal and

(mint)$ sudo mount /dev/sda4 /mnt
(mint)$ sudo mount /dev/sda1 /mnt/boot/efi
(mint)$ for i in /dev /dev/pts /proc /sys; do sudo mount $i /mnt$i; done
(mint)$ sudo chroot /mnt

(chroot)# apt-get --reinstall install grub-efi-amd64
(chroot)# exit

(mint)$ for i in /sys /proc /dev/pts /dev; do sudo umount /mnt$i; done
(mint)$ sudo umount /mnt/boot/efi
(mint)$ sudo umount /mnt
(mint)$ sudo reboot

After POST, the Debian’s GRUB2 menu showed and I’m once again able to boot into the computer.