In this case study, we are working on an iPhone 6 that has been water damaged and has come in for data recovery. This phone has been taken to multiple iPhone repair shops without any success. It is much easier to follow if you watch the video, however you can also read about the findings below. Getting started with this job, we find that the corrosion has already been cleaned from the previous repair shop. This is actually unfortunate as it means we cannot see where the damage was most severe. However, we move forward with what we can see. It is observed that there is still major corrosion around the image chip (chestnut) and it is also suspected that the power management IC most likely has corrosion under it as well. When it comes to iPhone Data Recovery, the best course of action is to remove unknown variables that may be causing problems. What this means is that we remove chips that are not necessary for data recovery, but can still be causing boot problems if they have shorts underneath them. For example, the audio chip is not required to turn on the phone (it would just have no audio if it was missing) but if it had shorted lines under the chip then it could be causing problems that would result in a dead phone.
Having said that, there are also chips that are absolutely necessary to pull data from the phone. Both the image chip and the power management chip are required for the phone to boot and for data to be pulled. When the chips are necessary but damage is still suspected, then we must replace those damaged chips with new ones.
Because of these facts, we pull up unnecessary chips and we also know we have to replace the image chip. Once it is up and the rest of the board is generally cleaned, we see if the phone is booting. There is no image with which to check if it has turned on, so we have to use a different method to see if the board is booting. This is done by connecting our DC power supply to the board and powering the board from that. It is observed that our DC power supply is getting hung up at a .05a draw. This draw indicates that the board is stuck in a low power mode and the CPU cannot boot past it. This low power mode is actually great from a diagnostic perspective. When the board is in this low power mode, it means it is time to start checking voltages as every voltage that can turn on, will. This is great as it helps us narrow down the problem line. In general, you measure all the CPU power rails, the NAND power rails, and i2c lines when you see this low power mode. In most cases, you will find a line that is not powering on within one of these 3 sections.
In our case, we find that the i2c lines as well as the 1v8_reset line under the image chip are not giving the proper 1.8v. These lines do not show short, they simple do not give the proper voltage. After some further measuring, it is determined that the power management IC must not be providing the proper voltage for these lines.
Because of this discovery, we replace the power management IC. Upon removal, it is confirmed that there was major corrosion under the chip. Once the power management IC is replaced, we again check with out DC power supply if the board is booting. To our delight, we see a DC power draw signature that appears as if it is booting. This means that the board is now capable of turning on, however we still have missing chips that we must replace in order to pull data; mainly the image chip and the touch chips. Without these chips, we cannot "trust" the computer and start the recovery process.
Once these chips are replaced we try to boot the phone normally from a battery and we do indeed see that image is working and the phone is booting. However, we run into one final problem in that the touch is still not working. This final problem is diagnosed by checking the touch voltage line supplies. We find that one of the touch power rails is short. We narrow down where the short is by injecting voltage and searching for the heat it supplies at the shorted component. It is determined that out new touch chip is actually bad and must be replaced a second time.
Once that problem is fixed, the iPhone turns fully on and we have access to the photos and other data for the customer!