There is something I’m missing here.
If you say you tried the “Computer doesn’t boot…” tutorial, but didn’t know how to boot to a TTY, what did you exactly try there?
In my opinion it’s worth trying to boot from a live USB, chroot into your system and update.
In this way, you’ll be automatically (without password) root into your system.
See here how to chroot.
I think the problem could come from here:
You’re missing the Nvidia drivers.
Maybe something went wrong during an update and the sudo dkms autoinstall could help.
Alternatively, either from TTY of chrooting, you could try:
sudo pacman -S nvidia-dkms nvidia-settings