iPad completely unresponsive, any advice before taking apart?

Question

iPad Pro 12.9" 4th Gen

Repair and disassembly information for the fourth-gen iPad Pro 12.9". Announced and released in March of 2020. Model A2229.

crwdns2934591:026crwdne2934591:0 crwdns2934593:0crwdne2934593:0

D Sully @dsully

crwdns2934065:0crwdne2934065:0: 23

2

crwdns2931729:0crwdne2931729:0: Huk 20, 2023

crwdns2933897:0crwdne2933897:0

iPad completely unresponsive, any advice before taking apart?

As the title says, my iPad is unresponsive: black screen, no audio signals when plugged in, no response to volume and lock button reset.

I had it in to an Apple authorized shop, they plugged in their tester and got nothing “static” on the line. Since my warranty is out I’d be looking at just replacing with a new model, $1500 baseline where I am.

I’ve done some phone work, replacing batteries, screens, cameras etc. but those issues are pretty self evident on what to fix. Any tips on trouble shooting this issue, be it checking over the charge port and cables, logic board, and battery?

Thanks for any support.

*****Edit*****

I’ve opened it up and the USB port seems fine, now I want to confirm the battery before completely gutting the thing. I found these 2 spots on the battery connector cable (blue arrows in picture), would this be the proper spot to check voltage? If so I got 0.01v across them which would seem the battery is shot for some reason. If someone has a better way to check the battery without first removing it I’d be happy to hear it.

final edit

I followed tear down procedures to remove the logic board to get direct access to the battery, I got 3.8v off that, so assumed it was a logic board issue. Had a third party tech check that out but found no faults, he reattached the screen and charge port and it booted like normal and everything seemed fine. I took it home, reassembled everything and everything runs fine except a few small lines of damaged pixels from being too forceful with the screen.

TLDR: took it apart and chased the gremlins out.

Big shout out to @flannelist for their input and advice, check the comments.

crwdns2934081:0crwdne2934081:0 crwdns2934083:0crwdne2934083:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0

crwdns2889612:0crwdne2889612:0 1

crwdns2934285:0crwdne2934285:0

crwdns2933313:01crwdne2933313:0

crwdns2934051:0crwdne2934051:0

Alisha C @flannelist

crwdns2934065:0crwdne2934065:0: 32.6crwdns2936485:0crwdne2936485:0

24

35

32

crwdns2931729:0crwdne2931729:0: Huk 20, 2023

crwdns2933897:0crwdne2933897:0

Diagnostically speaking I would want to try two things.

Plug into a computer to see if it is recognized although, at this stage I doubt it, it's still worth a try.
I would want to know exactly what sort of energy is going through the charge port. If you're actually invested, you can get a USB-C meter to tell you more about the power being consumed (or not) by the device. No power going through the charge port could mean a faulty port or battery, but even how much current and what voltages might tell you more.

UPDATE: If you want to check the voltage actually coming out of the battery, the most reliable way to do it would be to test the battery directly. This is a screenshot of an iFixit replacement, so no test points like your pic of the OEM battery. Red pad here is positive and blue pad is ground.

Here are the spots on the board that PPBATT_VCC (the line for battery power) travels after it gets to the board. You can use any ground point on the board to test against, The long gold strip along the edge of the board here is a ground pad. Anything in red in this picture is on the correct electrical line to test, but I would go for C8593 since it's bigger, and easier to test on.

crwdns2934105:0crwdne2934105:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0

crwdns2889612:0crwdne2889612:0 2

crwdns2944067:06crwdne2944067:0:

Thanks for the reply.

To your suggestions:

1. I tried plugging into a computer and it wasn’t recognized, nothing even showed up that a device was plugged in.

2. The Apple people tried their tester and said it wasn’t picking up any voltage but rather “static” in their words, which I kind of interpret as an open circuit. I don’t have access to a voltage tester like the one you reference but I connected my phone to it (they’ve cross charged in the past) but no reaction from either.

Again, thanks for the response, I’ll probably just have to open it and check voltages/continuity on the internals.

crwdns2934271:0Huk 20, 2023crwdnd2934271:0 D Sully crwdne2934271:0

@dsully Agreed. If they didn't get much on their meter (I'm not sure what they used, or what they mean by static either) this may be even be a simple charge port issue. Which is relatively easy on these. The port is modular anyway, rather than soldered to the board.

But if not, I would isolate the battery (any iFixit Guide for an iPad will include some methodology for this). Disconnect everything from the board except essentials (charge port and screen, power button might help). Then see if you get power.

crwdns2934271:0Huk 21, 2023crwdnd2934271:0 Alisha C crwdne2934271:0

@flannelist I got it opened and if you see my edit you’ll see where I am now, your insight would be helpful with this.

crwdns2934271:0Huk 25, 2023crwdnd2934271:0 D Sully crwdne2934271:0

@dsully Apologies for the delay in response. It took me a minute to figure out where these test points are, since they're on the battery side of the connector, not the login board.

But those look to be battery "gas gauge" lines. Those may be difficult to test, because they are lines for data. They tell the board how much charge the battery has left, and temperature data, that sort of thing.

I'll post an image in my original answer where to test battery voltage on the board, but it might also be necessary to test right on the battery.

Some backstory might also be helpful for context. This device just stopped working randomly?

crwdns2934271:0N'w 9, 2023crwdnd2934271:0 Alisha C crwdne2934271:0

@flannelist thanks again, yeah it pretty much just stopped. I was using it to stream shows one day, put it away and tried to use it a week or so later. I followed the the tear down procedures to where I could access the main battery contacts and got 3.8v from it. There was no damage noted on the logic board.

I brought it to a third party tech and he couldn’t find any faults, he reconnected the screen and charge port and it booted like normal, no actual repair needed. Must have just had to scare the gremlins out I guess 🤷

Thanks again for all the advice, hopefully others can benefit from all this.

crwdns2934271:0N'w 10, 2023crwdnd2934271:0 D Sully crwdne2934271:0

crwdns2934273:01crwdne2934273:0

crwdns2934285:0crwdne2934285:0

Thanks for the reply.

To your suggestions:

1. I tried plugging into a computer and it wasn’t recognized, nothing even showed up that a device was plugged in.

2. The Apple people tried their tester and said it wasn’t picking up any voltage but rather “static” in their words, which I kind of interpret as an open circuit. I don’t have access to a voltage tester like the one you reference but I connected my phone to it (they’ve cross charged in the past) but no reaction from either.

Again, thanks for the response, I’ll probably just have to open it and check voltages/continuity on the internals. — D Sully
@dsully Agreed. If they didn't get much on their meter (I'm not sure what they used, or what they mean by static either) this may be even be a simple charge port issue. Which is relatively easy on these. The port is modular anyway, rather than soldered to the board.

But if not, I would isolate the battery (any iFixit Guide for an iPad will include some methodology for this). Disconnect everything from the board except essentials (charge port and screen, power button might help). Then see if you get power. — Alisha C
@flannelist I got it opened and if you see my edit you’ll see where I am now, your insight would be helpful with this. — D Sully
@dsully Apologies for the delay in response. It took me a minute to figure out where these test points are, since they're on the battery side of the connector, not the login board.

But those look to be battery "gas gauge" lines. Those may be difficult to test, because they are lines for data. They tell the board how much charge the battery has left, and temperature data, that sort of thing.

I'll post an image in my original answer where to test battery voltage on the board, but it might also be necessary to test right on the battery.

Some backstory might also be helpful for context. This device just stopped working randomly? — Alisha C
@flannelist thanks again, yeah it pretty much just stopped. I was using it to stream shows one day, put it away and tried to use it a week or so later. I followed the the tear down procedures to where I could access the main battery contacts and got 3.8v from it. There was no damage noted on the logic board.

I brought it to a third party tech and he couldn’t find any faults, he reconnected the screen and charge port and it booted like normal, no actual repair needed. Must have just had to scare the gremlins out I guess 🤷

Thanks again for all the advice, hopefully others can benefit from all this. — D Sully

iPad Pro 12.9" 4th Gen

iPad completely unresponsive, any advice before taking apart?

crwdns2933313:01crwdne2933313:0

crwdns2934229:0crwdne2934229:0