masterpiece

You know the washable paint that they let you try out in the store that they swear works or you get your money back?
My 3 yo decided it would be a blast to write on one wall with crayons 'again' ,I scrubbed tell my arm felt like it was falling off and all it did was take the paint off and left the her master piece. Yes, as pretty as her picture is I have to find away to fix this .Maybe I will cover it with toothpaste then try to paint over it? Or scrub my wall until the texture is gone then try to paint?