I am on EndeavourOS and was running the core/linux kernel and used yay to update my kernel to probably 6.11.1arch along with some programs and Nvidia driver updates.
After rebooting it went to the login screen but when hitting login it stayed at a black screen till it fell back to terminal without gui.
In the grub submenu I tried fallback which had the same problem.
Fortunately I had LTS installed, and it worked.
So now what do i do? I am sure there are many solutions to fixing it. But do they work all the same? I could delete core/linux in AKM and reinstall it, right?
I am a beginner in Linux and would like to learn from this.
You can reinstall stuff without uninstalling it first (yay -S <package>). To add to the other comment suggesting a driver reinstall, you can use downgrade to revert back to old versions (and also to keep it fixed till you wanna give it another go, don't forget if you do so tho!).
Moreover, set up snapshots! They provide a very straightforward way to recover from failed updates.
If you are on btrfs, you need: snapper, snap-pac, btrfs-assistant (optional, but provides a GUI and more automation...)
If you are on ext4: timeshift, timeshift-autosnap
Im both cases you need to create a profile for root (/), although when it comes to Timeshift I think you need (/ want to) exclude /home. (On the default btrfs setup, you don't need to do this, because /home is it's own subvolume).
Next is to login and look at the logs, especially dmesg. Find out how to open a virtual terminal, probably ctrl+alt+f1 (or f2 etc) so you can bypass the display manager to login and poke around. Or try SSH from another system. There's a couple of ideas, good luck!
This happens to me often whenever nvidia (dkms) rebuilds and the module compilation fails (for whatever reason).
Usually I drop into tty ctrl+alt+f2 as root, run dkms autoinstall (or just yay -S <your nvidia package> should trigger dkms rebuild if needed) and then rebuild initramfs ( mkinitcpio -P), reboot.