"another version of this product is already installed"

Previously, I had an installation of Minecraft on a hard drive that failed. Attempting to manually reinstall resulted in an error, which is outlined here without real solution: https://bugs.mojang.com/browse/MCL-5194

Using the only suggestion present, I wiped all registry keys containing "minecraft" or "mojang". This now creates an error:

"Another version of this product is already installed. Installation of this version cannot continue."

There's nothing left for me to delete or remove. Attempts to use Window's repair tool here has failed:
https://support.microsoft.com/en-au/help/17588/fix-problems-that-block-programs-from-being-installed-or-removed

A complete scan of my computer and a deletion of any files containing "minecraft" or "mojang" has had no effect.

I'm out of ideas short of buying a new PC or reinstalling windows. Any other suggestions?