help my N7260

My nokia 7260 became white scree several days ago .It appeared two or
three times a day at first. But in the following days the screen become
white frequently.When it happened,I can operated it as usual,the only
difference is that i can't see what appeared on the screen.
So I turned to the KF,he told me my N7260 must live in a damp place or
have been watered,because there were some rust spot on the iron board behind
the mainboard ,which lead to loose contact of the screen.And he had no idea
to do with it.
Is there any people who can help me?
Is there any people who can tell me how to deal with the rust spot on
the board?
THANK YOU VERY MUCH
RAE