[trhway]

>How would this be able to land in the event of complete electrical failure?

this is why you'd have 2 independent set of rotors/motors and batteries (or other source of power). Each set alone at maximum power should allow for controlled descent. It may happen that in this "emergency" mode it can work only for limited time and become non-serviceable afterward, like the battery discharges beyond repair, etc...

Helicopters obviously don't have such an option so the engine cutting off puts you on a brink of catastrophe and requires highly trained pilot to avoid it. Electrically driven multi-rotors are completely different in that regard. With just a DMV driver license your grandma would be able to land one with half rotors off.

[iofj]

There are so many planes that cannot land in the event of complete electrical failure ... starting with every last modern passenger airliner. There the problem is that human strength is not enough to control flaps and hydraulics are too heavy (translation: possible but too expensive), but if the electrical infrastructure completely fails ... it's over. Plane will lose control, rapidly spin out of control and dive chaotically into the scenery.

It hasn't happened yet.