How do I restore my knowledge base from a Full Raw Backup (JSON)?

You can make a Full Raw Backup in json format to save all your data on

How do I import it back in? E.g. if I want to restore the backup from yesterday after I totally messed up some notes.

Related to How do I reset my entire knowledge base?, but I want to import a backup instead.

See for what I tried and what problems I encoutered.