yeah, there's no way to change bulbs on the cargo/third brake light..
i broke one open to put my own led setup in there, but i haven't had time to work on it.. its all engineered, just have to sit down and do it. i refuse to pay $300 for a new one that will have the same issues as this one down the road.
the water gets in thru the screw holes. the one i opened, that i got from a member here, clearly had water intrusion from the recessed screw holes where the sonic weld was broken against the backing. the gasket they use is not very good either, id say its a one time use..