Great Youtube mini documentary on this topic. It's fascinating that this happens and that even Australia uses these machines with cryptic UI and operations.
https://www.youtube.com/watch?v=SrDEtSlqJC4
Some further info:
Secret codes. Legal threats. Betrayal. How one couple built a device to fix McDonald’s notoriously broken soft-serve machines—and how the fast-food giant froze them out.
https://www.wired.com/story/they-hacked-mcdonalds-ice-cream-…
Crazy clickbait title.
Isn't this that media bias type things, kinda planting the idea that "McDonald's ice cream machines are always broken"?
From my experience, 19/20 times, the ice cream machines are working… there are times during summer where they over serve it and the ice cream is crap or they can't serve it but honestly, this statement is way over.