For the first time in nearly two years of owning my Model S and charging daily with the HPWC, I arrived at my car to find that it had not charged and the light ring was Red. I quickly noticed that the HPWC was not lit up at all (no green light). I figured it must have tripped a breaker, but checked and saw the breaker was fine. I then decided to press the "Reset" button on the side and it immediately started working fine. This must have happened very shortly after charging started because the rated range was maybe 1 mile beyond what I remember arriving with when I got home. Also, I was able to open the charge port door with the HPWC button, so the charger must have been working at least right before I had plugged in. I'm not terribly concerned as this is the first time this has happened in two years, but just curious if anyone else has had this happen to them.
I have not with the HPWC or UMC, but often "momentary" interruptions of utility power can cause this type of thing.
Does anybody know where the reset button is on the current HPWC (the first new version that allows slaving mode)? I can't find it in the manual, and if I have to open it, it would be nice to know to bring my screw tip set. Edit: it's on the outside left of the Wall Connector. It's a big red button that says Reset. No screw tips or any tools needed! Cover can remain on.