After upgrading to from fedora 22 to fedora 23, I was unable to boot into linux due to a kernel crash. I was able to load up the previous kernel from 22 to get back to desktop.
I thought it might be a bad grub config so I ran this to rebuild grub
grub2-mkconfig -o /boot/grub2/grub.cfg
This produced a lot of errors such as:
ERROR: pdc: reading /dev/sdb[Input/output error]
It looks like the initramfs could be corrupt.
sudo dracut --regenerate-all --force
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
No errors were produced at this time.