the only subdir that existed is 515.48.07 which happens to be the same version number as for pure nvidia.
just being brave and sudo rm -rf 515.48.07/ and yay -S nvidia-dkms followed by sudo mkinitcpio -P and the blank screen is gone! (nvidia was removed beforehand)
The persitance of all who helped saved me a lot of time to re-install EOS. Thank you!