I noticed in the brief it stated:

Your animation will begin with at least 3 different characters in a room. You may have more than 3 but must have at least a male character, a female character, and one-or-more zombies.

 

This means there has to be a zombie in the room before the lights go out. I thought the zombies only appeared when the lights turned back on. That’s ok, I changed my storyboard slightly.

 

While the male and the female are playing ping-pong, a zombie will be hiding under the table. Then the lights go out.

When the lights come back on, the humans and the zombies are getting ready to fight. Then the music starts to play and they begin to have a  friendly dance battle.