Usually when something goes wrong with a rebuild, the cause is displayed. Try rebuilding again and scroll up after it completes to look for the error message.
If you’re not getting anywhere, you can start fresh with a new VPS and restore your backup and try again.
You can post to Marketplace to ask for paid help, if this is urgent. Or consider official Discourse hosting! After spinning up your trial you can restore your backup, and get your community back up and running in no time.