That's what happened to me. Here is the before product:
I tried Mr Clean MagicErasers and a miriad of other cleaning products but nothing took of the marker.
Fortunatly my daughter recieved a new version of this exact you for her birthday,
I promptly threw out the permeate markers it came with and had her use Crayola washable markers as a friend had suggested.
Just for proof that it works. Here us the drawing stage:
Here is the wash off:
Here is Luna cleaned off and ready for a new design:
So throw out the makers and use washables for any "design-a-toy"!