SD870 encountered water. Screen is now white. Does the screen need to be replaced or electronic components?

you are asking about the screen Sharp LM12S49, what is the screen used in. laptop or similar unit, the electronics driving the screen probably had an electronic component going bad within one of the printed circuit boards, and needs to be tested to determine if the board can be refurbished, or damaged to the point of needing replaced. the screen showing white means that the screen is working but not getting the video signals that it needs to show a picture on it. please give more details of the model of the unit that this screen is used in.

The IXUS 860 IS is called the SD870 IS in some parts of the world. You may order an SD870 IS LCD assembly from here.

It is damaged and must be replaced. If the LCD screen is the only issue I'd be surprised. Saltwater is extremely corrosive to electronic parts. If enough water got on the LCD to cause damage chances are very good it got into the camera as well.

A screen that far damaged cannot be repaired at home. Inquire about the cost of repairs on Canon's website, then decide whether to do the repair or scrap it.

i would not recommend it other than maybe a keyboard duster, the problems your are encountering sounds like cable issue symptoms. have you tried swapping out the cable.

u need to replace lcd display sorry cant help it

There is a problem with the flash or flash charge circuit. It will need to be repaired and may cost about $ 100 if not under warranty,

Sounds like the Backlight is working but the LCD is not. The first thing I would try is opening up the camera(if this is the sort of thing you are comfortable doing) and pulling out and then pushing in the LCD ribbon.

See this image for where the ribbon for the lcd connects (at least on a SD600).
http://3.bp.blogspot.com/_XmSxWfvnwsE/RlOsEjYjN5I/AAAAAAAAADs/0OuqTpB0GRc/s1600-h/plugin.jpg

Dissasembly guide for canon powershot (likely good for sd870 IS)

Touch the screen to pause playback and display the movie control panel. 2. Drag up across the screen to increase the volume. Touching the volume indicator displays the volume panel.

Check the antenna cable, also provide details on make and model.