Update to 2.9.1 failed

I ran the updater to go from 2.9 to 2.9.1 but the installation failed. There was no error message or anything – the program simply closed mid-update.

Now I cannot uninstall or re-install and trying to manually download the 2.9.1 installer simply gives me an error “download failed – connection timeout”.

I tried running the installer from an older version, which appears to install OK, but the program fails to launch.

Any thoughts or ideas on what else I can try?