Started an update on the latest kde plasma. It was a lengthy update so I left to let it do it’s thing. The computer was off when I returned, and attempts to boot were unsuccessful. on booting, the message
error: file ‘/boot/vmlinuz-5.18-x86_64’ was not found
error: you need to load the kernal first.
Attempts to boot in other kernels or fallback mode cause the system to hang during the boot process.
Sorry for the limited info. Slow typing this into an iPad.
Any help would be much appreciated.
is there any message when you tried booting different kernel, or just a black screen?
do you have a manjaro usb?
The fact that your computer was shut down was probably due to a power outage, and what you describe here-above is indeed what happens when the machine is shut down during an update.
The package manager first downloads the packages, and then it removes the kernel images and initcpios at the beginning of the actual update process, and only when all packages have been upgraded does it put the new kernel images in /boot, recreates the initcpios, and then updates the bootloader configuration.
What you need to do to remedy this situation is boot up in the live mode of the USB stick or CD/DVD that you used for installing — or any other recent Manjaro installer medium — and open up a terminal window. Then, type the following commands… 
sudo su -
manjaro-chroot -a
[ -f /var/lib/pacman/db.lck ] && rm -f /var/lib/pacman/db.lck
pacman-mirrors -f5 && pacman -Syyu
update-grub
Let the process finish, no matter how long it takes. Then, when the command prompt returns, leave the chroot environment by either pressing Ctrl+D or by typing the command…
exit
Repeat that in order to close the terminal window, and then cleanly reboot your computer, making sure that you remove the removable drive in time.
Beside what @Aragorn said, you’ll probably need to manually install whichever kernels you had before.
Thank you for your help!
A thunderstorm did pass near the area, but not directly over us. It is possible that we had a brownout at the time of the update.
I have run the commands as specified:
[manjaro /]# [ -f /var/lib/pacman/db.lck ] && rm -f /var/lib/pacman/db.lck
[manjaro /]# pacman-mirrors -f5 && pacman -Syyu
::INFO Downloading mirrors from Manjaro
::INFO => Mirror pool: https://repo.manjaro.org/mirrors.json
::INFO => Mirror status: https://repo.manjaro.org/status.json
::INFO Using default mirror file
::INFO Querying mirrors - This may take some time
1.788 New_Zealand : http://manjaro.mirrors.theom.nz/
1.232 Netherlands : https://manjaro.mirrors.lavatech.top/
0.587 United_States : https://mirrors.sonic.net/manjaro/
1.600 Singapore : https://mirror.freedif.org/Manjaro/
0.216 United_States : https://coresite.mm.fcix.net/manjaro/
::INFO Writing mirror list
::United_States : https://coresite.mm.fcix.net/manjaro/stable
::United_States : https://mirrors.sonic.net/manjaro/stable
::Netherlands : https://manjaro.mirrors.lavatech.top/stable
::Singapore : https://mirror.freedif.org/Manjaro/stable
::New_Zealand : http://manjaro.mirrors.theom.nz/stable
::INFO Mirror list generated and saved to: /etc/pacman.d/mirrorlist
:: Synchronizing package databases...
core 165.3 KiB 787 KiB/s 00:00 [################################################################] 100%
extra 1849.7 KiB 2.80 MiB/s 00:01 [################################################################] 100%
community 7.1 MiB 2.89 MiB/s 00:02 [################################################################] 100%
multilib 180.5 KiB 2.03 MiB/s 00:00 [################################################################] 100%
:: Starting full system upgrade...
there is nothing to do
[manjaro /]# update-grub
Generating grub configuration file ...
Found theme: /usr/share/grub/themes/manjaro/theme.txt
Found linux image: /boot/vmlinuz-5.17-x86_64
Found initrd image: /boot/intel-ucode.img /boot/initramfs-5.17-x86_64.img
Found initrd fallback image: /boot/initramfs-5.17-x86_64-fallback.img
Warning: os-prober will be executed to detect other bootable partitions.
Its output will be used to detect bootable binaries on them and create new boot entries.
ERROR: mkdir /var/lock/dmraid
Adding boot menu entry for UEFI Firmware Settings ...
Found memtest86+ image: /boot/memtest86+/memtest.bin
done
[manjaro /]#
Is the error message
ERROR: mkdir /var/lock/dmraid
a problem?
When attempting a clean boot it displays this message and freezes immediately afterwards:
MANJARO-21.2: clean, 2035574/242114560 files, 2115125295/968430676 blocks
Only if you’re running a software RAID configuration, but even then still it would be weird, because I don’t think dmraid is used all that much anymore.
That message is normal — it’s just the regular boot-time filesystem check — and probably hasn’t got anything to do with why the machine hangs. But the hanging itself isn’t normal, and I have no idea why it does that. 
Thank-you for your help. This group has been phenomenal in supporting its users. This is very much appreciated.
There could be any number of ‘holes’ in the software if the update process was interrupted. It was a sizeable update of several GBs. Would there be any hope of recovering this installation? Or would it be necessary to do a new install?
Any suggestions?
reinstall kernels from chroot like zbe suggested …
post output from chroot from this:
mhwd-kernel -li
Well, someone other than me might come up with certain things to check for, and there are plenty of threads here at the forum about freezes at boot time, so perhaps best to look around and wait for better advice. 
Outputs as follows:
[manjaro /]# mhwd-kernel -li
Currently running: 5.15.57-2-MANJARO (linux515)
The following kernels are installed in your system:
* linux515
* linux517
* linux518
if you were trying to boot with the 5.17 you would be stuck … this kernel is end of life so remove it:
mhwd-kernel -r linux517
reinstall the other two:
pacman -S linux515 linux518
then post output from:
mhwd -l && mhwd -li
Please see output text below:
[manjaro /]# mhwd -l && mhwd -li
> 0000:03:00.0 (0200:10ec:8168) Network controller Realtek Semiconductor Co., Ltd.:
--------------------------------------------------------------------------------
NAME VERSION FREEDRIVER TYPE
--------------------------------------------------------------------------------
network-r8168 2016.04.20 true PCI
> 0000:01:00.0 (0300:10de:1382) Display controller nVidia Corporation:
--------------------------------------------------------------------------------
NAME VERSION FREEDRIVER TYPE
--------------------------------------------------------------------------------
video-nvidia 2021.11.04 false PCI
video-nvidia-470xx 2021.11.04 false PCI
video-nvidia-390xx 2021.11.26 false PCI
video-linux 2018.05.04 true PCI
video-modesetting 2020.01.13 true PCI
video-vesa 2017.03.12 true PCI
> 0000:05:00.0 (0280:14e4:4365) Network controller Broadcom:
--------------------------------------------------------------------------------
NAME VERSION FREEDRIVER TYPE
--------------------------------------------------------------------------------
network-broadcom-wl 2018.10.07 false PCI
> Installed PCI configs:
--------------------------------------------------------------------------------
NAME VERSION FREEDRIVER TYPE
--------------------------------------------------------------------------------
video-linux 2018.05.04 true PCI
video-nvidia 2021.12.18 false PCI
network-broadcom-wl 2018.10.07 false PCI
Warning: No installed USB configs!
just to be sure lets reinstall also the video drivers:
uninstall them:
mhwd -r pci video-nvidia
mhwd -r pci video-linux
install them again:
mhwd -i pci video-linux
mhwd -i pci video-nvidia
any error post here, if there are none, reboot
The command
mhwd -r pci video-nvidia
threw an error as follows:
[manjaro /]# mhwd -r pci video-nvidia
> Removing video-nvidia...
Sourcing /etc/mhwd-x86_64.conf
Has lib32 support: true
Sourcing /var/lib/mhwd/local/pci/video-nvidia/MHWDCONFIG
Processing classid: 0300
Sourcing /var/lib/mhwd/scripts/include/0300
Processing classid: 0302
checking dependencies...
error: failed to prepare transaction (could not satisfy dependencies)
:: removing nvidia-utils breaks dependency 'nvidia-utils' required by cuda
Error: pacman failed!
Error: script failed!
The command
mhwd -r pci video-linux
ran fine but terminated with these comments:
:: Running post-transaction hooks...
(1/2) Arming ConditionNeedsUpdate...
(2/2) Refreshing PackageKit...
Error connecting: Could not connect: No such file or directory
error: command failed to execute correctly
xorg configuration symlink valid...
> Successfully removed video-linux
Due to the errors on the first of these two commands, I did not yet install the drivers.
do you use cuda?
Not that I am aware of.
so remove it:
pacman -R cuda
then:
mhwd -r pci video-nvidia
install them again:
mhwd -i pci video-linux
mhwd -i pci video-nvidia
any error post here, if there are none, reboot
It did throw an error, not sure if this is critical:
[manjaro /]# pacman -R cuda
checking dependencies...
:: blender optionally requires cuda: cycles renderer cuda support
:: openmpi optionally requires cuda: cuda support
Packages (1) cuda-11.7.1-1
Total Removed Size: 3915.24 MiB
:: Do you want to remove these packages? [Y/n] Y
:: Processing package changes...
(1/1) removing cuda [##########################################################] 100%
:: Running post-transaction hooks...
(1/2) Arming ConditionNeedsUpdate...
(2/2) Refreshing PackageKit...
Error connecting: Could not connect: No such file or directory
error: command failed to execute correctly
post output from:
pacman -Qs cuda
Please see output below:
[manjaro /]# pacman -Qs cuda
local/icu 71.1-1
International Components for Unicode library
local/lib32-icu 71.1-1
International Components for Unicode library (32 bit)
local/openmpi 4.1.4-1
High performance message passing library (MPI)