Fusible traces aren’t uncommon - but they would effectively destroy the device if current limits are exceeded, and they certainly would be if the power supply is non-isolated, so it wouldn’t actually be a solution to the firmware update problem.
The usual solution here is an optical coupling of some kind - optocouplers (a box with a LED, photodiode, and air gap between them) are very common for this purpose, and are an inexpensive and effective option for digital signaling across an isolation boundary.
In this case they’ve basically built a custom optocoupler out of discrete components, which is a bit unusual, but makes sense when you consider the risk of corrosion due to water ingress at the diagnostic ports, and the need to access it while - for example - a dishwasher cycle is running.
It was originally a switching/signalling waypoint, and later started seasonal passenger service for skiiers in 1932, before later switching to year-round service. Apparently it used to be a popular hiking destination as well, but with the establishment of more convenient rail and road routes became less popular in the 80s.
Actually, writing (selling) a put is the short position. Buying is the long position; you profit if the value of the put goes up (which happens when the value of the underlying stock goes down or is expected to go down).
I don't know about your company, but where I work shorting my employer's stock is explicitly against company stock policy. It really does make sense though, you don't want allegations of insider trading going around when employees start shorting stock...
The usual solution here is an optical coupling of some kind - optocouplers (a box with a LED, photodiode, and air gap between them) are very common for this purpose, and are an inexpensive and effective option for digital signaling across an isolation boundary.
In this case they’ve basically built a custom optocoupler out of discrete components, which is a bit unusual, but makes sense when you consider the risk of corrosion due to water ingress at the diagnostic ports, and the need to access it while - for example - a dishwasher cycle is running.