You have to investigate as to why named does not start other wise reinstallation has no use.
Named is not installed by custombuild but by the operating system by the way. It's amongst the pre-install commands.
Try (re)starting named via SSH and see what error it gives. If it shows something to look in journalctl -xe or something like that, use that and see what the error is and post it here so we understand what is going on and what could be the issue.
Often in /var/log/messages (on RH alike systems) one can see what error is displayed.