Have you attempted to run the upgrade manually? The upgrade process creates a backup of existing installation folders/files and copies them back. I have seen instances where the backup/restore failing due to insufficient permissions, even though the upgrade process is run with admin access.
Have you tried to run the upgrade interactively by downloading the installer? This will allow to check the progress/install log by right clicking on the install steps, assuming the process moves that far.
The other thing to check is checking the existing folder/files permissions and updating them (the Windows administrator may be able to help/check)