rebooting with new kernel

[Paul Cartwright]

I did a dnf update, got the new kernel,
uname -a
Linux pauls-server 4.0.7-300.fc22.x86_64 #1 SMP Mon Jun 29 22:15:06 UTC
2015 x86_64 x86_64 x86_64 GNU/Linux


rebooted and... a blinking cursor on a black background..
this seems to happen everytime now when I get a new kernel in F22,
x86_64. So I boot a boot-repair CD, redo the grub, and reboot with a
grub menu.
my F22 is /dev/sdb6, and when I do a grub2-mkconfig it finds all of my
OSes on sda & sdb. once I manually do the grub2-mkconfig & grub2-install
/dev/sda I can reboot & grub shows all of my OSes. But if I just do the
dnf update, get a new kernel, and reboot.. blank. Not sure what the
update does, but it obviously takes out my grub install, not sure what
it replaces it with. what should I look for, or what am I doing wrong?

-- 
Paul Cartwright
Registered Linux User #367800 and new counter #561587