We (@redford, @mrtick and I) have reverse engineered the PLC code of NEWAG Impuls EMUs. These trains were locking up for arbitrary reasons after being serviced at third-party workshops. The manufacturer argued that this was because of malpractice by these workshops, and that they should be serviced by them instead of third parties.
The McDonald’s ice cream machines have a similar vibe, but that doesn’t seem to be as smartly/evilly executed as these trains. Remote kill switches are insane.