Canon PowerShot S120 lcd is appearing as a negative image?

I dropped camera in water for about 5 seconds. dried in rice.

camera works and takes pictures, but lcd shows as a negative. sent to best buy they said it was not repairable but gave no explanation. i noticed that replacement screens are available for purchase and diy repair is possible. My question is: Does anyone have any thoughts as to whether the negative image is related to a motherboard issue or to the lcd? Wanted to get any feedback before taking a chance on replacing the screen. Thanks, John