I know for shure that WD40 will remove wax crayon and it my work for candle wax, for instance when my kids have drew on the walls with wax crayons i have used nothing but WD40 and a cloth and it comes of with very little effort.
I would first try with a hair dryer and a lint free cloth to remove the thick of the wax, after that i would use WD40 with a lint free cloth and finally i would use a lint free cloth soaked in luke warm water and a little bit of washing up liquid, wring the cloth out untill it's slightly damp and rub the screen over.