I’ve seen the failed to umount /oldroot etc before, my issue with the message (I don’t have the boot delay) is solved by adding shutdown to /etc/mkinitcpio.conf. It probably is one of the solutions you run into when searching for the error. The xhdi_hdc error might be worth exploring further for. That seems to stop the halt process.
Some more old links that might be pointers to solutions.
It seems that showdown issues are not that common as say startup issues and even less solved/posted about.
