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High performance tablet computer released by Apple on November 11, 2015. Model A1584.

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iPad Pro continues to power cycle after battery replacement.

My Gen 1 iPad Pro was power cycling at 3-10 second intervals when on a stock charger and cable. It would not power on at all when not connected.
I replaced the battery with one direct from IFixIT. The iPad now will power on for a period of 1-5 minutes. I have also noticed the battery will not charge past 49% and the indicated percentage drops rapidly when not on a charger. Ex. 49% directly to 29% then 13% within minutes.
Open to trying anything. Would love to get this repaired for my Grandmother.

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When you say it powers on for 1-5 minutes, what happens at the end of that time? Does it shut down or does it reboot?

da

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Hi Kyle,

Believe it or not, it actually sounds like you're making progress. I agree with Gorilla that this does sound like a battery issue and we'll address that in a minute.

First I'd like to introduce you the the concept of a kernel panic. That phrase describes the sequence of events that occurs on an iOS device when it encounters an unrecoverable error. Generally that happens when the operating system goes through its sensor scan procedure, which happens every three minutes. If for some reason it has a problem with any given sensor, it logs the error and then reboots the phone in an attempt to recover from the error.

Of course, the problem here is that with a hardware error, the next time it goes to scan the sensors, the error will still be there and will result in another kernel panic, saving the log file and rebooting the phone. We haven't gotten to the point where the phone is actually smart enough to say to itself, "Hmm, I've rebooted a dozen times and the problem is still there, so rebooting again probably isn't going to help", and as a result it will continue rebooting to infinity and beyond.

The key part of this is the log files I mentioned. Those are stored on the phone, and with three minutes between reboots, it's actually enough time to get to one of the files and see what's in it. The excellent Kernel Panic wiki page authored by our very own Alisha (@flannelist) has instructions on where to go and how to get to those files.

iPhone Kernel Panics - iFixit

So I'd say the next step for you is to read through the wiki page and locate the latest panic log, then come on back here and add the first page or so to your question via cut and paste, a screenshot or a photo. That information should point us in the direction of exactly what's causing the iPad to reboot and from there we can recommend a course of action.

Now, that all being said, based on the existing information we have, it does sound like an issue with the battery communication. There's a small circuit board built into the battery called the BMS, or Battery Management System, that has things on it like the temperature sensor along with ways to determine the battery health and voltage and/or current sensors. So the motherboard has to communicate with the battery in order to work correctly, which it doesn't sound like yours is doing.

Although @xingxing is absolutely correct that either of the problems they mentioned could cause what you're seeing, there's a third possibility that's much more common, and that's damage to the connector on the battery. We tend to see it happen during the step where you insert a battery blocker to disconnect the battery while you are in the process of removing the screen. There are three extra pins on the battery connector that are used to communicate with the BMS, and if those get bent or broken, then you get behavior like what you're seeing. Here's a picture of those pins.

Block Image

If one of those pins isn't making contact for some reason, that would explain what's going on. It's not quite as likely of an explanation in your case since you're using a brand new battery, but whenever you use the battery blocker there's a possibility of damage to those pins.

I hate to suggest it, but once you have the panic logs and we've had a chance to take a look a them, I'd say you are probably going to have to take the whole thing apart again and remove the battery so you can verify that the pins are intact and not damaged. Let's get those logs first, then we can talk about what to do next, though. Here's how to add that information to your question.

Adding images to an existing question - iFixit Repair Guide

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Very detailed and informative! I always learn something new from your posts :D

da

That is incredibly helpful. Thanks for your reply.

My only issue now is that during the troubleshooting process, I hard reset the iPad. Now it won't stay on long enough through the initial setup to get to the kernel panic logs.

Regarding the battery pins, I was careful during assembly knowing issues with bent or misaligned pins could arise. That being said, I am to the point of deciding if an additional disassembly is worth it. I may be cutting my losses at this point. It's tough to push on when this generation of iPad can be bought refurbed for ~$200.

da

@kyleduensing Yeah, I feel your pain. Alisha, (@flannelist), is there a way to read the panic logs using a computer in DFU mode or something?

Assuming you don't find any damage to the pins, it definitely looks like there's something hinky going on with the battery. iFixit warranties their batteries for a year, so it might be worth your time to contact them and see about getting a replacement. In my experience they've been very helpful. Best way to get hold of them is via email at support@ifixit.com.

da

@dadibrokeit Possibly? I have never checked to see if a panic log will register to any software if if it's in setup mode.

This sounds to me like bunk battery data for sure. The battery data pin is often to blame (as @dadibroke it already mentioned) Unfortunately I do not have a schematic for this in my stash. So it's a little tricky to say for sure exactly what parts might be involved in that. It's also possible, the charge port could be faulty.

If you have a multimeter, I would see if you can get a voltage reading on the battery itself. You can check voltage on the two large pads on the battery. It should read at 3.7 volts (or more) if it is reasonably charged.

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That erratic battery behaviour is likely a sign of bad power management IC, or there's a slight chance you received a faulty battery.

Block Image

@kyleduensing PMIC is the chip in green square, I don't know of any tests you can do to check for functionality (maybe with a multimeter), I usually judge by symptoms - things like random reboot, abnormal battery charge/discharge with a new battery, OS update recovery error 40xx.

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Is the power management IC integrated into another component? Any tests I can do to verify?

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Kyle Duensing sarà eternamente grato.
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