Is secure boot enabled? mokutil --sb-state
will answer that.
If secure boot is enabled then the nvidia modules cannot be loaded unless you
- disable secure boot in the bios setup menu
or - sign the modules so they can be loaded with secure boot enabled.
It is late enough that I cannot remain to walk you thru this, but signing the modules is relatively simple
- follow the steps in the file
/usr/share/doc/akmods/README.secureboot
to generate the key and enroll it in bios. (the commands require the use of sudo) - remove the unsigned modules and rebuild them with
sudo akmods --force --rebuild
- reboot