I naively ran a big update (pacman -Syyu) on my Manjaro Linux PC after about 3 years of not using it. What can I say… I have become rusty, and should have expected something to go wrong there.
When I boot now, after the GRUB menu I am shown the following:
Starting version 251.2-3-manjaro
[FAILED] Failed to start Load Kernel Modules
[FAILED] Failed to start Load Kernel Modules
[FAILED] Failed to start Load Kernel Modules
And then nothing.
I am able to Ctrl+Alt+F2 to a tty and log in there, but I am at a loss on how to diagnose the issue.
Eventually I will do a clean install. But for right now, if someone could help me through the steps to solve this, you would really help me out of a bind. Please let me know what information you need.
Thanks!
Possibly due to a residual “EOL” kernel and/or a broken update, from after three years of no updates.
Is a fresh install out of the question?
Three years between updates on a rolling distro, curated or not, is still a very long time.
Unfortunately a fresh install would be difficult until this problem is fixed, because I no longer have a live USB drive. I cannot create one on my work MacBook, because mass USB storage devices are disabled on it. 
When you have access to the console, installing a LTS kernel and seeing if this will boot some gui
sudo mhwd-kernel --listinstalled Will show installed kernels.
sudo mhwd-kernel --list will show available kernels
sudo mhwd-kernel --install linux510 will install a supported LTS kernel
I had 419 installed. After installing 510, I am still shown the “Starting version …” line, but no error messages this time. Then it goes to the black screen (with blinking _ cursor). Still, no GUI is loading. 
journalctl --boot --priority=3 --catalog
will print the errors from the last boot and might shed some light on your issue.
Ah, indeed, that looks interesting. Let me type out what I’m seeing:
<time> michiel-pc systemd-modules-load[361]: Failed to find module 'nvidia'
<time> michiel-pc systemd-modules-load[361]: Failed to find module 'nvidia-drm'
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc kernel: kvm: disabled by bios
<time> michiel-pc gdm-launch-environment][1501]: Glib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
<time> michiel-pc gdm-launch-environment][1518]: Glib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
<time> michiel-pc gdm-launch-environment][1524]: Glib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
<time> michiel-pc gdm-launch-environment][1530]: Glib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
<time> michiel-pc gdm-launch-environment][1536]: Glib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
<time> michiel-pc gdm-launch-environment][1542]: Glib-GObject: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
The problem, to me, seems that you are missing some new nvidia packages that got changed a while back.
Depending on that kind of driver you want to run:
sudo mhwd -a pci nonfree 0300 for the closed nvidia drivers
sudo mhwd -a pci free 0300 for the open source nouveau drivers.
Beautiful! I needed to delete some old nvidia packages first, but this worked like a charm!
It surprised me a bit that it didn’t even require a reboot. After the install, I was immediately sent to my GDM login screen. 
Thanks so much! You’ve saved me from some headaches there. I owe ya!