Forum unavailable with redis error in unicorn logs (

Did it fail on the backup or the restore?

It would be helpful if you actually included the weird error,but if it was on the restore I suspect that it is the one described here: Restore failing with missing chat_mention function

If that’s correct, my advice is to wait. If waiting is not an option, you could try seeing that the site you restore has the same commit as the site that create’s the backup.