For reference, it was already on Hacker News a few times :
Polish trains lock up when serviced in third-party workshops: https://news.ycombinator.com/item?id=38530885
Dieselgate, but for trains – some heavyweight hardware hacking: https://news.ycombinator.com/item?id=38567687
Polish Hackers that repaired DRM trains threatened by train company: https://news.ycombinator.com/item?id=38628635