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Hello, I have an iPhone XR which doesn’t turn on. It is not water damaged, and hasn’t been dropped. It shows no signs of life, and is not shorted. I tried hard resetting but nothing happened. When I plug it into the DC power supply and press the power button, it goes to 0.023 amps and doesn’t increase or decrease. Does anyone know what this issue may be? Thank you
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From experience 0.023 amps would mean it is going straight into DFU mode. You could try and see if it is recognised with iTunes but most likely it will not.
There could be a number of reasons this is happening. You can start by measuring the voltage on the NAND and CPU power rails. If these rails are there you will then need to check most of the reset lines. If all these are good it would point to a communication problem between the NAND and CPU.
If it has suffered a drop it could have cracked one of the CPU coils, you might have to at least remove that shield so you can do a visual exam.
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I also has the DFU mode thought, just don't have any experience specifically with the XR to know that 23 mA would be the magic number, since I see primarily MacBooks, but will keep this in mind. This sounds like solid advice to me.
Update: I tried connecting it to iTunes, with no luck. However, I did notice something strange with the current when a charger is plugged in. When a charger is plugged in, the current drops from 0.023 amps to 0 amps. This happens with a wall charger and even when it is plugged into my computer. Could this possibly be the issue, and if so do you know what may be causing it? The CPU and NAND power rails all tested fine, and it seemed they were communicating fine together. I did also remove the shields, and everything looked fine.
@Colby Morris It is normal for the current to drop to zero when a charger is connected. What you have is a brain dead phone. The CPU is waiting for instructions or is giving them and the NAND is not receiving them. You have proved that by confirming the power rails are producing the correct power for the components to work.
If the reset lines are okay there are only a few paths you can go down.
• The most common at the moment would be a board swap but this would only be economical if it where for data recovery.
• Test all the CPU data lines with an Oscilloscope.
• I think there is one pad under Tigris and a couple under the Hydra IC’s although extremely rare can cause this current draw.
• Remove the NAND and see if it is recognised in DFU. You will probably find it is. Check the NAND with a programmer than check the NAND pads on the board. If they check out right you defiantly have a CPU problem most likely a cracked solder ball from a drop.
I will try that, thank you so much for your help!
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Hi! Another problem the phone could be having is that it just did a software update. My mom used to have an XR and those phones are known to have the BSoD after an update. Sadly that can't be fixed. Other answers that are on this post could also be why ist not turning on. Hope this helps!
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Is any current draw occurring before you attempt to power? Do you have any other components connected when getting this reading? When you say it's not shorted, what specifically is not shorted?
I would suggest taking the board out, if you haven't yet to see if the issue is the same with no components connected. After that just look over the board as best you can, I don't remember how much of that board has shields over it, but even if it's the whole board, likely some just have stickers on them you can peel off. I know parts are REALLY tiny so it's hard to tell, but see if anything looks off: dull grey, singed, corroded, cracked, bent etc....
If you have a DC power supply, do you also have a multi meter? Do you have experience with micro soldering?
由 Alisha C 完成的
Hello, there is no current draw occurring before I attempt to power the phone on. I tried powering it on with all components connected, then tried to power it on with all non-necessary components disconnected. Both tries failed. When I say it is not shorted, I mean when I turn the DC power supply on there is not an immediate large current.
I have taken the board out and have given it a thorough inspection under a microscope, and everything looked good. I am trying to not take any shields off unless strictly needed, so I'm not sure about the components under the shields.
I do have a DC power supply and a multi-meter, and a lot of experience with micro soldering. This phone has confused me though. Thank you for your comment!
由 Colby Morris 完成的