I'm running Devuan, which doesn't have systemd, so the instructions for the shutdown script don't work for me.
I'm wondering if the script is needed any more. The page says:
I assume that that means that there was some kernel feature that was not working when the product was released, but I'm wondering whether it has been implemented since then.I think that it needs lots of time to fix that behavior. so I recommend using this script as a workaround
I'm running kernel versions 4.14.141+ and 4.14.28+ on my two boards. Both are from the oph.mdrjr.net repository.