Chosen Solution
My daughter dropped her iPhone 6S from her back pocket into the toilet, but she caught it before it was totally submerged. She waited a day and tried to turn the phone on, which when it didn’t respond, she attempted to charge it. I opened the case a week later and there was no noticeable water or residue. I did a visual inspection of the battery which looked ok and tested ok with a multitester. I am not sure how to test the logic board or the LCD, how do you do a diagnostic test on these?
The problem with iPhones is that you can’t see the damage done with your naked eye most of the time. In your case, it sounds like there was damage to the charging system which led to the phone not booting. Unfortunately, time is your enemy and charging it for sure is your enemy. Here are a couple of videos that explain water damage and how to treat it: https://www.youtube.com/watch?v=DsDpALKQ… https://www.youtube.com/watch?v=plmElKA6… There isn’t much in the way of a diagnostic test for a phone that won’t power on. You can take the phone apart and examine the logic board under a microscope. After that you can repair any and all damaged components. This does take micro soldering skills and equipment. Start with the charging circuit and work your way up from there.
