I just upgraded my newly installed KDE Plasma and now I am stuck on Memtest forever. Help anyone? I can't even exit out of this everytime I do It starts again.

Ah, the charm of updating linux distributions.
I remember the days of updating would cause X11 to break. Back when I had only a few years of experience. Helped me get better tho at navigating the etc configuration.
Good luck man

Looks like either your bootloader somehow got corrupted, or your disks got reordered.

Grub default fucked up?

Try hitting escape or arrow up/down on boot. When the grub menu comes up, select advanced and then the most recent non fallback kernel. Hope that helps.

I rebooted the pc and installed KDE all over again. Now it's fine.
I think what I did wrong was that after the installation I started the system upgrade of about 1.5gb. And at some point it looked like it got stuck so I forced turn off the pc and then that happened. So never interrupt a sys upgrade i guess. But thanks for your comments :)

@unicorndev I think that's the general rule for all OS's 😅