I installed the latest update from fedora 39 using ‘discover’ update manager on 2nd February 2024.
When I try restarting the computer it gets stuck with my motherboard logo and fedora loading icon and then the loading icon also disappears and I am left with the motherboard logo with a fedora icon
This sounds like the nvidia driver may not have been properly updated and/or became corrupted when you updated to the 6.6.14 kernel.
Just in case, I would suggest doing the following.
remove the existing module with sudo dnf remove kmod-nvidia-\*
repair the module with sudo akmods --force
after step 2 completes reboot.
It is mandatory the with a kernel upgrade you wait for at least 5 minutes after the update completes before rebooting to allow adequate time for the new nvidia driver modules to be properly compiled and installed. The steps above will remove the possibly corrupted modules and should properly compile new clean modules.