id reccomend taking the thing appart, and try to clean the lens, it could also be (if your device has optical focus (identifyable by faint clicking noises when it focusus) and water coming in there, and leaving ressidue in the mechanism, this can be fixed by washing yoour immage sensor in 96% alcohol in a super clean container, and let it dry out (make shure to not add any impuritys to the alcohol like water or using a container with impuritys in it