Last night, the Blink was in a typical "behaving badly" mode, where you couldn't connect to it via the network. It was charging the car at the time. I have read somewhere, and I couldn't find the thread, that if you tried to go to "settings", it would hang at that point. I saw this for myself. My recollection about the discussion was, that it would recover after the charging was done. But I was kinda concerned that it might not come out of charge mode. When I checked subsequently, the screen had turned off. Tapping it brought it back on, but it was still "processing". Well, I figured, since the screen saver was working, and that's like the most difficult bit of programming Blink has done to date,

I got a "charge complete" message from the car at 4 AM. When I checked on the Blink, it was still in the same state as before. Not responding to the network, screen saver operation, sitting at "processing", and, as a bonus feature, it was pretending to charge (now showing 8-1/2 hours of L2 so far

But my question is, if the AC supply were not cut off for some reason, can the car stop charging anyway? It takes some serious hardware to interrupt 3-4 kW of power supply (hence the loud "thunk" inside the box). So I'm not sure if the car could "refuse" it.
Happily the evidence is in favor of the EVSE not doing this, but that isn't the question. And it is a serious safety concern, at least from the battery's standpoint.