This was posted by @sentio_florian to the slack channel #sentio_bugs with the note:
Hi everybody, we cooked a start of diagnostic process here, this is the same process that we use internally for diagnostic/troubleshoot, we will update it from time to time.
Please note that we will still require users having trouble to go threw[sic] our support team.
If you decide to follow the process on your own, please make sure to follow *all* steps in that order, and do not skip any. Otherwise, the result will be different, and you might harm your superbook.