Does anyone know how to fix the screen being dim?

So i left my phone on the coffee table with my 2 year old and needless to say she got ahold of my phone and spilled grape soda. I did all of the right things, put it in rice in a container for a few days whiched worked great however the whole screen lit up dim (every screen). It was okay at first i could still see the pictures and everything but as the days went on the screen just kept getting more and more dim, now it is to the point where i almost can not see what is on the screen. Other than that the phone works great and it charges and everything. I dont even know where to start to solve the issue. Please Help!