What finally worked for me was to remove the PC from our domain back to workgroup. Then the install of Office 2016 worked. I then rejoined the domain and all was well.
I was able to make this work without removing from the domain. Simply logged on as local admin instead of a domain account to do the install.
Out-of-the-box Dell PCs running 1803 (I did Windows Updates before doing the domain join, so not sure if that matters).
My attempts were:
- Run the .NET fix - no help
- Uninstall/reinstall .NET 3.5(2.0) - no help
- delete the two registry keys - no help
- had two going at once
PC1: removed from domain, installed as local admin, worked.
PC2: left on domain, but logged-on/installed as local admin, worked.
Thanks for the tips saving a wipe/reinstall of a minutes-old PC.