What's the best way to recover data from corrupted iPhone 6s (iTunes not working/iCloud not used)
If you only need to get the notes from your backup, just download third party application to extract your notes from the Backup ( but if that is encrypted, most softwares ask to decrypt the backup first. So I assume 27th November backup is not encrypted) 

After the extraction of Notes from backup, restore 27th November backup to iPhone and import those Notes from the PC (Which you are extracted from backup) 

Import notes from PC : https://support.apple.com/en-gb/HT205793

It is not quite possible to repair a corruped iTunes backup because mainly those are encrypted. So you best shot is what I described. 

I think you have asked that whether these provided links applications are reliable and clean. I've used DrFone program personally and that wasn't quite satisfying. But that could be great for you since that has good ratings. Give a try to find out which program is the best for you to do your task.