When we go to buy an iPhone from the Apple Store, we do so under the assumption that we are getting a top quality product because we are paying a top tier price. While this normally is the case, it is also a fact that Apple products are not perfect. The iPhone 12 Pro is the newest model iPhone available at this time. However, it appears that some of the
design flaws are already coming to light, less then a year after the initial release. To begin with, disassembling this phone down to the motherboard is more difficult then any iPhone in the past.
iPhone 12 Pro Motherboard
In all iPhone models of the past, unscrewing the screws that hold down the board was all that was required to remove the iPhone Motherboard and start microsoldering and data extraction techniques. With the iPhone 12 Pro however (US version), we now have the 5g antenna soldered to the back of the motherboard, routed around the battery, and screwed into the side of the iPhone housing. This is a problem because the battery is up against screws, making them impossible to unscrew unless you first remove the battery.
iPhone batteries are adhered down with strong adhesive and the unexperienced will have a hard time removing them, and will possibly destroy them. In the past it was common to simply replace the battery if it was damaged and the phone would operate normally. With the newest iPhones however, an annoying message will constantly pop up that reminds you that the battery inside this phone is not its original. This message cannot be disabled so it is quite the annoyance for customers and is simply a tactic Apple uses to try and discourage independent repair. Moreover, Apple will no longer honor their warranty if the battery has been replaced. This is not necessarily a bad design decision, but it does make the lives of those who work on these boards much more difficult.
Once we have the motherboard out, we start the diagnostic process.
Detecting a Motherboard Short
Our first step at finding the problem with this no power iPhone is to connect our DC power supply to the battery connector and try to boot the phone with this power instead of battery power. When we apply voltage to the battery connector we notice that there is an immediate amperage draw. This is not normal. Normally, the phone will not draw any amperage until the phone has been prompted to boot by way of pressing the power button or plugging in the charging cable. This indicates that there must be a main line power rail short to ground on this board. We know this because the short to ground is what pulls that amperage when it is not supposed to be pulled yet, as voltage always looks for the fastest pathway to ground. This is a great find, as it gives us a hard indicator of where we should be looking for our problem; on the main power rails and specifically on VDD_MAIN. Once this is known, we measure VDD_MAIN with our multimeter and confirm that is short.
Now that we know which line is short, we have to find the specific component on that line that is bringing the whole line down.
iPhone 12 Data Recovery - Short is Found
Now instead of applying voltage to the battery connector, we can apply voltage directly to the shorted line. We know there is a short on this line, we know that voltage likes to find the fastest pathway to ground, and we know that voltage meeting ground creates energy in the form of heat. This means that whatever component that is shorted to ground will heat up when voltage is applied to the line. We can take advantage of this by applying freeze spray to the board and visually inspecting where the heat first occurs once voltage is applied.
With our freeze spray and voltage in hand, we find which component is short. Once the component is identified we simply remove that component, clearing the line of all shorts. Once the line is clear, we can now attempt to boot the phone and extract the data and pictures for our customer.
The problem with this finding is that the customer did absolutely nothing wrong, and this event still occurred. The iPhone itself was in perfect physical condition and there was no water damage present. Still, a VDD_MAIN short spontaneously appeared and compromised the users data, less then a year after the release of this new model. These new models iPhones cost up to $1500 so when they fail less then a year after purchase, it really indicates a problem. We can only hope that this is a one off exception, but only time will tell if these types of problems will continue to spontaneously occur in the iPhone 12 series.