Device Rename in HAADJ environment

The script that Durrante posted is from Michaels page, he was for a long time the head of Autopilot at Microsoft so he knows his stuff. Only problem I had with his script was that it runs in the users/computers context and if the object existed in AD it wouldn't have the needed permissions to delete the old object, and would then fail to rename because the object already exists. That's why I wrote mine and run it through SCCM with an AD admin level account so it can do the object cleanup and not have to grant everyone full permissions. The other option you can do is to modify his script, the schedule task part, and tell it to run as an account with full AD permissions, the risk there is username and password would be easy to extract from the script.
In the script you can add the -user & -password switch to the register task part
Register-ScheduledTask -User SYSTEM -Action $action -Trigger $triggers -TaskName "RenameComputer" -user"USERNAME" -password "PASSWORD" -Description "RenameComputer" -Force

I am on weekly calls with MS and a few of their engineers for Autopilot and I have been asking for the %SERIAL% option for about 2 years now. They tell me its not even on the roadmap yet and may never be for Hybrid Join.