Create a Live USB using installer ISO

I'm using Endeavor OS, which is a lightweight near pure Arch experience.

1. Download ISO from the website
2. Use a tool to create a bootable USB. Balena Etcher has worked well for me being cross platform and I've verified using it on Mac & Linux.

Boot into the Live USB

Boot the installer ISO, make sure to go to the desktop and not run the installer itself. Set up wifi and open up a terminal.

Mount system partitions

1. Find out your OS partitions and mount points.

   Command

   $ sudo lsblk -f

   Output

   NAME      FSTYPE            FSVER LABEL                       UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
   sda                                                                                                               
   └─sda1    linux_raid_member 1.2   anirudh-media-rig:RAIDArray 8fd231ac-10a0-ef7f-6a35-ea843e5d05e4                
   └─md127 ext4              1.0   RaidArray                   61f77751-5640-4efe-9636-8f037fe9585a  193.8G    90% /run/media/anirudhm/RaidArray
   sdb
   ├─sdb1    vfat              FAT32                             61AC-3D1B                             389.7M    61% /efi
   ├─sdb2    ext4              1.0   endeavouros                 1d857b70-35c1-44a4-8a49-47bc14dbfe37   27.8G    67% /
   └─sdb3    swap              1     swap                        34c900d9-bcd8-439b-aaf0-b535accebf81                [SWAP]
   sdc                                                                                                               
   └─sdc1    linux_raid_member 1.2   anirudh-media-rig:RAIDArray 8fd231ac-10a0-ef7f-6a35-ea843e5d05e4                
   └─md127 ext4              1.0   RaidArray                   61f77751-5640-4efe-9636-8f037fe9585a  193.8G    90% /run/media/anirudhm/RaidArray
   sdd                                                                                                               
   └─sdd1    ext4              1.0   A001                        f1df7479-c73e-435d-8d27-38d46995b53c  785.3G     9% /mnt/usb-Samsung_PSSD_T7_S6XBNS0W601267V-0:0-part1

2. Mount your main system partition. Above that's sdb2 for me.

   $ sudo mount /dev/sdb2 /mnt

3. Mount your ESP (EFI System Parition), if you are using one (identified in the step above if /efi or /boot/efi are present). Above that's sdb1 for me.

   $ sudo mount /dev/sdb1 /mnt/efi

Now your system is mounted.

Log into the installed system

Now you should be able to use enter a chroot to log into your installed system using arch-chroot.

Command

$ sudo arch-chroot /mnt

Example verification

[liveuser@eos ~]$ sudo arch-chroot /mnt
[root@EndeavorOS /]$ ls /home
anirudhm # Your actual system's user should be present here

Re-install kernels

Now the most common issue is a broken systemd-boot (or grub), or a broken kernel installation. To fix this we now just need to re-install the kernels and reboot our system.

1. Make sure packages are up to date

   $ sudo pacman -Syu

2. Install regular and LTS Kernels (LTS is more stable and can be used on boot in case the regular doesn't work)

   $ sudo pacman -S linux linux-lts linux-lts-headers

3. Restore kernels and initramfs (and bootloader entries) - EndeavorOS Only

   $ sudo reinstall-kernels

4. Reboot your system and unplug your live USB

And we're done! Hopefully this does the trick to restore your Arch/EndeavorOS install to working condition.