You can soften the box of your pointe shoe with rubbing alcohol.

Rubbing alcohol is preferable to water because is dries more quickly.  lightly soak a cotton ball in rubbing alcohol and dab across the box of the shoe at the place where it should bend on demi-pointe.  Never pour the alcohol or water directly onto the shoe as that could weaken too much of the shoe and make it unwearable.   After softening the boxes in this manner, it is especially important to allow them to dry out completely before wearing.

rubbing alcohol on pointe shoes