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Repair information and guides for the 2015 Retina MacBook Air. Model A1534

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Keyboard and trackpad not working after battery replacement

After doing a battery replacement in this Macbook A1534 2015, the trackpad and keyboard stopped working.

The keyboard backlight and power button still work, but the trackpad, haptic feedback, and the rest of the keys are dead.

External USB keyboard and mouse work through an Apple USB-C to A adapter.

After first reading about this problem, it looks like it was the flex cable from the mainboard to the trackpad that was damaged during the repair. I ordered a new one, but no change to the problem.

After this, I did a continuity check on all the pins on the flex cable with a multimeter and found that one of them did not have continuity. Then I tested the original flex cable, and the same pin did not have continuity on that one either. Because I didn't test the new cable before installing it, I now don't know if this pin is supposed to have continuity or not. Pictures show which pin I am talking about (pointing to the same pin on both ends of the cable).

Block Image

Block Image

I have tried to reseat the flex cable connector multiple times on both ends, resetting PRAM, booting in safe mode, and tried to do a SMC reset. SMC reset did not work, as this does not seem to work with an external keyboard (but I have disconnected the battery multiple times, which does the same thing as far as I know).

Now I feel a bit stuck on what to do and would greatly appreciate all help I can get to solve this problem.

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Just had the same but slightly different failure behavior. But somehow fixed it (described below) after a bunch of random trials. Probably some kind of keyboard/trackpad subsystem firmware corruption problem.

Poor Design / Assembly Direction

First the whole design kind of sucks. Keyboard/Trackpad flex is pulled before battery disconnect AND connected AFTER battery connect. Prior to pulling the flex on disassembly, there is a button on logic board to press for 10-15s 3 times per this direction (my LED never lit up). Maybe some kind of magic step is necessary during assembly as well. Didn't see any mentioning in a couple of guides. Seems like bad stuff can happen trying to insert the flex with new battery already connected.

Glued on battery means if you want to tested it before gluing it on, this flex will be reattached with battery power connected at least 2x if not more. More chance to go wrong. My problem didn't start after the first test, rather few dis/reassembly later (1 time forgot to connect power button flex, 2nd time discovered LCD flex was slightly crooked and no screen etc. Each keyboard trackpad connect after battery connect seems like risk to corrupt the keyboard/trackpad/

Problem Symptom

First time I discovered the problem was when computer was slow booting up. All keyboard trackpad input was sluggish. Keyboard backlight was flickering and different keys had different brightness in random pattern.

Of course natural instinct is to disassemble + reassemble which goes through the above mentioned poor design problem once again. And probably a few times just to check your work, inspect cable connections etc.

Eventually, there was no more keyboard and trackpad function (keyboard backlight black) during macOS but they do work in a couple of places

  • up to about midway during macOS boot, they work then macOS gets to a point where its probably loading drivers, then stopped working.
  • work in diagnostic mode
  • work in network update
  • even worked booting in safe mode
  • But these behaviors started changing in my sequence of repair attempts listed below

System Report->More Info->Hardware->SPI shows no keyboard/trackpad. Heck even webcam didn't work on Photo Booth (camera hardware present in System Report) App comes up, green webcam light on. No pic showing, can't take pics.

Note I've connected BT keyboard + mouse at this point to further diagnostic inspection.

First Repair Attempt

Found this post with popular solution, Read the most popular answer by maffoo

Why is my keyboard/trackpad not working?

Tried it with MB running in all kind of state. Didn't work.

2nd Repair Attempt

Thought maybe load Win10 and see what its drivers does. Went through bootcamp and started installing win10, noticed win10 boot during install still no keyboard+trackpad. Decide to preempt this long effort and powered off, (vaguely recall I may have SMC reset here) restart and Mac boot goes into some kind of weird mode booting back to macOS with a spinning wait icon was in front of Apple logo on boot process... Strange looking so I force reboot it again a couple of times but it always did this so just let it do what it was trying to do. Eventually got got back into macOS, keyboard+trackpad was working! keyboard backlight no, webcam+PhotoBooth working.

Tested with a reboot (can't remember if was cold reboot) Still working. Decided to push my luck and do SMC reset... and back to square one : no keyboard + trackpad. Although webcam + PhotoBooth now stayed working.

Tried a bunch of SMC reset with macOS running in various state (diag mode, booting up, network recovery) nothing worked.

3rd Repair Attempt

Started reading about people saying could be firmware since it works sometimes (1/2 way of boot, diag mode, net recovery etc) Decided to try originally shipped macOS so network recovery to El Capitan. Didn't work. Left it over night, next morning same problem. Network recovery back to Big Sur, Didn't work. Reboot a couple of times and eventually, keyboard + trackpad was working! after macOS booted up. Yay, keyboard backlight shows the crazy brightness patterns noted above. Pressed keyboard backlight brightness down to 0 and backup. No fix.

Rebooted again and magically keyboard backlight is now perfect.

This is the current state. MB warm reboot, cold boots, sleep, wake all perfect. Not daring another SMC reset for now haha.

What fixed it?

Who knows but perhaps it has something to do with going back to El Capitan and back to Big Sur triggering some kind of keyboard trackpad firmware reload? My guess is keyboard/trackpad subsystem's firmware got screwed up by the poor power before flex assembly sequence. Keyboard trackpad is not some simple dumb device. Definitely some microcontroller and therefore firmware in there.

Maybe even multiple microcontrollers? (1 for keyboard, 1 for trackpad, 1 for backlight) and one has to work before helping to reload the next one? Thus my observation after keyboard/trackpad started working, one (or maybe 2?) more reboot was necessary for trackpad.

Maybe Genius Bar have tools that can reload these firmware directly. Don't know. They usually just to tell you to be new devices on harder problems haha.

Long winded post but thought I provide full context for someone else puling their hair out on this.

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1+ week follow up. Decided to zap PRAM and the keyboard backlight started randomly flashing/flickering brightness again on individual keys. But the track pad and clicking was working fine.

Proceeded to PRAM reset a couple of more times and a CMOS reset. Dial down keyboard brightness to lowest will turn off the key backlight. Didn't help. Left is sleeping for awhile and PRAM reset again and magically went back to normal. Did a couple of more PRAM reset and stays normal...

Also disassembled the rMB again to epoxy fix the floppy screen hinge ( How can I tighten the hinges on this model? ) and this time had no problem on the first disassembly (kbd+pad ribbon disconnect). But on 2nd disassembly, had crazy flashing keyboard backlight again. A few reboots later fixed it.

I guess follow up with more PRAM tests in a week time haha

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Hi howard, i’ve been scouring the web for someone with a similar problem to mine, and i’m finally so glad to have come across your comments.

My problems started too with an attempt to fix the wobbly hinges on my 2017 rMB. After assembling, the left speaker no longer worked, and similar symptoms to you appeared:

1) Backlight of the keyboard constantly flashing

2) Trackpad dying after login screen

3) Keyboard dies at the same time, though there was an instance of it continuing to work

4) Both worked in recovery mode and throughout the reinstall of the OS, but froze up in safe mode + once in the terminal & disk utility of the recovery screen

I’ve downgraded from Ventura to High Sierra, and miraculously the left speaker suddenly worked again! But both trackpad and keyboard still failed.

I’ve been suspecting my Flex cable too, as the macbook is known to operate trackpad + keyboard on the USB for pre-os but changes to SPI in MacOs.

Could i trouble you to provide an update on your situation?

Thanks!

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Mine worked for awhile after the El Cap -> Big Sur reinstall but I didn't use it much. Just powered on periodically to check battery charge. Unfortunately after 1-2 months. Problem has returned (crazy flashing keyboard backlight and dead trackpad after using it with a USB camera (problem seems to start after pulling USB camera cable from USB-C port, don't now if this is correlation, will test again once I get it running again). This happens near the end on OS (El Cap) boot which is probably the stage where its loading final macOS drivers) So clearly basic boot level drivers work but probably don't have all functionality (no keyboard backlight as an example) and somehow more advantaged driver encounters some problem with the keyboard+trackpad module (which probably has its own firmware)

Reloaded El Cap again, booted up with same problem. A couple of reboots was able to keep trackpad + kbd working while kbd backlight flashed like crazy so can setup the machine. Reboot didn't fixed anything. But a SMC reset followed by PRAM reset seems to have fixed it (for now) Did an addition 2x PRAM and 2x SMC+PRAM reset and kept on working fine. Will latest macOS (Big Sur for 2014 rMB) next.

Perhaps my prior "randomly got it working" after hinge repair didn't do the proper SMC+PRAM reset sequence. Although I did try proper SMC+PRAM reset while having this problem just now under Big Sur without success. So going to go with the sequence original macOS (El Cap) reinstall -> SMC/PRAM reset (fixed the problem) -> Big Sur (final macOS for 15 rMB) -> USB-C camera plug/unplug test and see if can keep it all running. For now, I'm going to guess the original macOS install requirement + SMC/PRAM reset to properly load/initialize the kbd/trackpad firmware.

Note the proper SMC reset sequence on rMB is 1) unplug power 2) press/hold left shift + control + option for 7s 3) add press/hold power button with step 2 keys for another 7s 4) release all keys and I waited for another 10s before PRAM reset

Maybe need to replace the top case with kbd/trackpad but am concerned same problem will occur with the replacement kbd/trackpad since will follow the same dis/reassembly steps. Seems the weakness of this design is connecting keyboard + trackpad AFTER battery connection. Maybe it is necessary to press the button near the battery connection to properly shutdown logic board prior to kbd+trackpad connection. If so, this is unmentioned anywhere.

UPDATE:

Just encountered keyboard backlight go dark gradually on one side, turn up/down kbd backlight and went back to normal but trackpad stopped working. Then I did a shutdown (seems like it just went to sleep because started up super fast) and magically everything fixed... Weird.

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Is there any damage on the trackpad itself? If the trackpad fails on these then both the keyboard and the trackpad will go out. I'd recommend trying to replace both the trackpad and the trackpad flex cable. If doing that does not resolve the issue, then my best guess would be that the cause of the problem is an issue with the top case itself or an issue with the main logic board. Good luck!

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There is no viable damage on the trackpad itself and it was working as intended before the battery replacement 🤔.

My biggest fear is that something has happened to the main logic board as I did not use a low power, power supply when first plugging it in after the repair as is advised to do in iFixit's guide, but as the system seems to work as intended, I hope nothing bad has happened to it.

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Have tou resolve the problem ?

I have exatelly the same probleme, i tried to change 3 flex cables but trackpad and keyboard dont work.

Please respond me if you have a new information of course

Thank you dear

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