iPhone got a few drops of water in now lcd's wont work

my iphone 6s got a few drops of water in it , i disconnected battery and left it to dry for 3 days , switched back on , worked for a min , then lcd turned off , so i got a replacement screen tried it on another iphone 6s first , then plugged it in to the water damaged phone and no display , but the phone works , i restored it via itunes , etc can hear it ringing etc , just lcd will not work , maybe damage to motherboard , but where do i look , thanks for any help