Water damage no power after clean and battery replacement

Hi all have been working on iPhones for quite a while now and repaired a few water damaged iPhones all which needed cleaned and new battery's.. But I have a water damaged one here now I cleaned it then new battery and nothing tryed a new screen and nothing. its not the backlight as I have checked for a faint image. Unplugged battery and tryed the dock and nothing. Is there any1 that has experience with this shed some light on it?

And the new battery does work have tested it in another phone thank you