We had an iphone 7 plus in recently after our customer had cleaned the phone after water damage and the phone would still not turn on. The water damage was minor and had only affected the top of the board.
Upon inspection we had a 5 amp short on VDD main. We checked over the board and found that capacitors C2609-2611, where all very corroded and needed replacing. We removed these components and tested again, unfortunately the short was still present. We then removed the CPU shield to inspect this area. The shield had not been removed so cleaning of the board could not have been done properly, after removing the shield we found a lot of corrosion above the CPU covering capacitors and resistors. We cleaned the board and saw that there were still several components that were visibly corroded, most seemed minor and we did not think these were a problem. We probed around in diode mode and found one nasty looking capacitor C3325 on the speaker amp line that was short. We removed this capacitor which cleared the short on this line and on the VDD line too, these lines where linked through U3301
We plugged the phone into our power supply and it booted up normally, we tested the basic functions and all seemed fine. We then cleaned the board and reassembled the device and returned it back to our customer who was very happy to return the device to its owner fully working.
We love working on water damaged devices as the owners are always so happy to get their phone and more importantly their data back!
If you have a water damaged device with important photos on please feel free to get in touch. We love a challenge!