Since I'm not into forensics I can't tell what really happened inside the components. That's also why I never said that the yaewsbm was the cause of the problem. Perhaps this module was just unfortunately in the wrong place at the wrong time. Or it had a fault which was not obvious. We'll most probably never know...
ESD is a pain. I've actually an Etherwave Pro on my workbench which was mute after a spark while the owner touching the volume loop. The obvious problem, a defective diode and a transistor in the volume detector circuit, is fixed but the pitch PCB which normally shouldn't be affected has still sporadic and temperature dependent issues...