Okay, answering my own post, just in case someone else has this issue.
So the root account is locked. So boot off a Centos 7 LiveCDROM, select troubleshooting, Troubleshooting mode does not find the installation so don't bother.
Enter a shell.
and chroot to /dev/sda7
then when you have a bash shell, passwd root
give root a password, this overcomes the lock, then you can check using journal the issue.
In my case, it was /dev/sda6, which needed to have xfs_repair run on it.