jeffjarvis, 
Fascinating #cybersecurity & #RighttoRepair story: Train manufacturer allegedly built kill-switch if locomotives repaired elsewhere; MacGyver hackers found the workaround just in time:
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Their Trains Were Stalled. These Hackers Brought Them Back to Life.
https://www.wsj.com/tech/cybersecurity/hackers-trains-disabled-poland-1b1f501a?st=nqsmoey6ktrsg14&reflink=desktopwebshare_permalink