I just upgraded to F16 and it went fine.
But I have a kernel issue and was able to hang it and after I did that and a hard powerdown,
my F16 does not find the boot block apparently.
It will boot if I put in a USB with an old grub .97 boot block.
I've tried installing the boot block to the hard drive but apparently don't have the right mojo.
grub2-install --no-floppy --recheck "(hd0)"
grubby says it's there: