1.40B is available to download here: https://cdn.www.elektron.se/media/downloads/digitone/Digitone_and_Digitone_Keys_OS1.40B.zip
I’m not sure if they pulled 1.40C, as I can’t find it.
The release notes only state:
List of changes from OS 1.40B to 1.40C
Support for updated production process.