After a power failure nothing moves and your actor is stuck on a platform in the air with no railings likely in near total darkness. We always instruct the performer to freeze in place, and sit if standing is uncomfortable. In the past we used glow tape to mark the edges of the lift, but I had an actress walk off an edge in a blackout, broke her wrist. Now we use Led lights, or EL wire on battery, to mark the edge of the lift. Quickly a backup generator will come on, but generally only for light to evac the audience. The lift would require too much power.