My son has just been given a Venus flytrap but, in transit, all the leaves closed up. When will they reopen?

When traps are triggered without any live captured in them, they will open in a day or two. The warmer the Venus flytrap plant is kept, the sooner it will reopen. There is no concern about the plant dying. I almost always trigger all the traps on my plants when I repot them, and they recover just fine.