Man crushed to death by robot in South Korea

could this have been prevented by just making sure the power was 100% off (unplugged, no battery) while working on it?

I saw this too, and there really isn't enough information to know if the robot is actually AI. There are a lot of kinds of sensors, like just basic sensors for grip, that allow for small tightness adjustments. Even if the sensor was visual in nature, it is unlikely to be advanced AI - most likely a simpler form such as OpenCV to detect the location of a box, for example.

To say mistaken for a box of peppers, is... an unlikely production robot. Expect that in a few years though.