shower floor

I'm not sure where to ask this so I thought I'd start here.About two years ago I installed a corner fiberglass shower on a bathroom redo.We put cement on the floor pressed the styrofoam floor on it then continued on the normal install.Today while fixing a slow drain, The h/o said "Oh! By the way the floor in the shower is cracked."IT IS 2"X3" in the letter J.I would like to put either a thin tub fitter floor or membrain and tile on the floor.I really don't want to rip everything out and start over any help on finding this product? It is an Aqua glass corner shower 3 year warranty.Thanks