<snip>
Your system was most likely rebuilding the initrd, and you interrupted it leaving you with a broken initrd.
Try booting off a rescue disk and chroot into the install, and run:
dracut -f -v
to regenerate all the initrds.
Also, you don't need to reinstall the kernel but just do a 'yum update' to get everything up to the latest release. The shim package with the fix is the latest.
-- Jonathan Billings billings@negate.org ___
Jonathan et al:
On the assumption that all the updates should now "just work", I did a from-scratch reinstall of a minimal Centos 7 system starting from netinstall and added software that I've always added (perl, dhcp, mariadb, etc). I did not exclude shim, etc in "/etc/yum.conf". After all the updates, the system was NOT bootable.
I repeated the install and updates, but this time including the line in /etc/yum.conf exclude=grub2* shim* mokutil and ended up with a usable system.
This was not the result I was hoping for.
David