Chosen Solution
So I have a 6S which has been totally submerged In water and unfortunately the person did try to turn the phone back on, and did not do anything special to try to get the moisture out. I have looked at all, or at least in all the places which I could access with a microscope and no components seems to have any obvious damage to me, except maybe U5411_RF and / or C5403_RF, but thats a maybe ? I have cleaned the motherboard in alcohol. Anyway, the phone does not boot up and does not respond at all when powering the phone from either a battery or with a charger. So where could I start measuring, at which components and places would be suitable to start testing?
Firstly I would check for a vcc main short. It most likely will have one. How you track it down depends on what tools you have. Freeze spray, flir cam or the old fashioned way with your tongue. Update (05/16/2019) C4127 would be the best to check vcc main.
