I was looking at the wrong place yesterday during your visit. Found the culprit at last. Two copper tracks were burnt, possibly by an accidental short circuit on circuit board during the recent installation on the second car. It wasn't caused by incorrect wiring. A small puff of smoke should be seen during the incident.
Luckily it only affected the failsafe as the main injection circuit is independent to the failsafe section.
See red arrows.
