I’m still under warranty will animas replace my pump because it has a crack?
I would say so but call them.
They replaced mine when I mine had the rubbery covering on the buttons come off. And I was out of warranty, although we were in the process of getting a new one anyways.
Animas generally is pretty good about replacing pumps, but if the crack is due to overtorqueing the battery cap or reservoir nut, you may be in for a fight. Or maybe a reduced-rate repair. Only one way to find out. 
I had a funny response to the title, "Ping has crack in it"...lol