Touch ID stopped working / blocked / unbound

[SYS_64738]

I have a MacBook air M2 and I have purchased a USED logic board with Touch ID included.
This would have been an upgrade from 8GB/256GB to 24GB/1TB by swapping the board and button.

I swapped out both the board and the included button and Touch ID worked fine but True Tone was missing.
I then run apple diagnostic and it complained about the ambient light sensor.

At the time I was unaware of this limitation so to see if light sensor still working I reinstalled the OLD logic board but left the NEW Touch ID in the cassis.
I have then run apple diagnostic again and the ambient sensor issue was gone but now it complained about Touch ID.
Of course I expected this since the OLD board was running with the NEW button.

After the above findings about the light sensor I wasn't so sure if I want to go ahead with the upgrade so I wanted to revert the machine back to stock.

I reinstalled the OLD touch ID and accidentally installed the NEW logic board with it.
They just look the same. I mixed them up mistakenly.

I realised it when I tuned it on, but just out of curiosity I guess, run an apple diagnostic to see what happens.
So of course as expected the Touch ID did not work nor the ambient sensor and True Tone.

So far there is nothing that couldn't be explained and understood. The problem will come later just keep reading.

To summarise what happened.
I run the NEW logic board with the OLD Touch ID and run apple diagnostic.
I run the OLD logic board with the NEW Touch ID and run apple diagnostic.

After this, neither of the logic boards accepted either of the Touch IDs.
They don't seem to be damaged at all in any way.

The likeliness I have damaged both Touch IDs is in my opinion very slim. I handled them very carefully. They are still working as a button. When I try to add a new fingerprint in macOS it just say "Failed Unable to complete Touch ID enrolment.", and in apple diagnostic I have an error "There may be an issue with the Touch ID sensor. Reference Codes: BMT005".


Since the Touch ID connects to the sub logic board, I thought may be I damaged the flex cable between the logic board and the sub logic board, or the sub logic board itself got a fault.
So I have then sourced another Macbook air M2 that WORKED FINE.
Removed the logic board and Touch ID and put them away... far away.
Let's name them LAST logic board and LAST Touch ID.
That had a sub logic board and a flex cable verified working so I kept those in there.

Then installed the OLD logic board and OLD Touch ID.
Touch ID still does not work.

Then installed the NEW logic board and NEW Touch ID.
Touch ID still does not work.

Just in case I mixed up the buttons I then tried all other combination.
OLD board and OLD button.
OLD board and NEW button.
NEW board and OLD button.
NEW board and NEW button.

F**K! Then I drank a whiskey..

Reinstalled LAST logic board with LAST Touch ID and that one still works fine.

So it seems like by mixing up the logic board and Touch ID blocks the functionality even if you later reinstall the correct board with the correct button. Or may be running apple diagnostic caused this not just simply macOS.

I DFU restored the OLD board with OLD button. Touch ID still does not work.

I also initiated a diagnostic suite session online on get support.apple.com to run an online diagnostic.
When I run the MRI interestingly the Touch ID was marked with a green tick.


But when I run the actual Touch ID test it came back with the error "Finger Enrolment Test Couldn't enrol the fingerprint."


I looked up the price of a new Touch ID from apple Self Service Repair Store would cost me £66.43 with free shipping.
https://support.apple.com/self-service-repair
After fitting it and running apple diagnostic I would be able to initiate System Configuration session.
I am assuming here this option in apple diagnostics wouldn't appear because of the replacement Touch ID itself but the fact that the self Self Service Repair Store would enrol a session for the serial number of my machine and upon connecting to wifi and apple server it would allow me to run it.
This is all theoretical here as I have no inside knowledge of how this works exactly.

I just feel like you know there is nothing wrong with this original Touch ID.
It would be nice to get apple to authorise a System Configuration session.
The OLD MacBook is out of warranty.
As we all know apple is apple so I do not think they would do anything with this even though everything is the original in the OLD machine now. I feel they will want me to pay for a new Touch ID or nothing else they could do.
Because I could just say "this is the original hey I want to run configuration utility please" and....

They probably would believe me right? 😂🤣
No. Probably not.

But may be I am wrong so I have booked an appointment to a local Genius Bar.
Of course any news I will update here.
But in the meantime if anyone has any ideas, don't hold it back.

I found the following in apple newsroom:
"for repairs involving biometric authentication, such as Touch ID or Face ID, System Configuration links the biometric sensors to the Secure Enclave on the logic board"

If swapping the Touch ID unlinks the original Touch ID from the logic board, then this is the next level of apple's effort to make our lives happier. Thank you apple! 😠

Question time...
Has any one experienced anything like this before?
Is there a fix for the issue?
Do you have any ideas what to try?

Any input would be much appreciated.

 

[SYS_64738]

First, I contacted Apple Support via web chat.

I didn’t want to make them fully aware of what had happened, so I just told them the following story:
"After erasing the Mac, it didn’t boot, but a link was displayed to the Apple Support restore page.
I completed the restore using another Mac and a USB cable, and now macOS works, but Touch ID does not."

They were very helpful and super nice, but other than running diagnostics, they couldn’t help me.
All they said was that this is a hardware issue, and I need to visit the Apple Genius Bar.

I went there today, and this time I was fully transparent.
I told them I had run the logic board with another Touch ID installed, and when I put the original one back, it no longer worked.

Again, they were super helpful and welcoming—great customer service. Eventually, an engineer came out from the back. He was given a rough idea of what I had done, then listened to my story again. Carefully choosing his words, he said—without admitting anything:

"Interesting. The only thing I can think of is that this MAY have happened because the Touch ID and the logic board are bound together. Due to security reasons, if the Touch ID is replaced, the logic board blocks its functionality."

I nodded and agreed—I believed the same.

He explained that “here at Apple,” the way they fix this is probably not what I wanted to hear: replacing both the logic board and the Touch ID together.

Then he gave me a quote—somewhere in the range of £460–£490.

I asked if it could just be re-calibrated, but no. “We don’t do this here.”

All of this was said in a very nice way.

The engineer also commented that I was the first person to come in for this reason.
I’m not entirely sure if that’s a good thing—should I be proud of myself for tinkering with tech, or feel completely stupid for not knowing this would happen? 🤣😂🤣😂

But in my defense, I haven’t come across anyone mentioning this issue anywhere online.

Still, I’m not done just yet—I’m going to try one more thing to fix it.

You see, Apple now sells parts—not directly, but through an authorized company that sells genuine, brand-new Apple parts. Apple also provides repair manuals for them.

The repair manual for the MacBook Air M2 (2022) guides me through replacing the Touch ID, and at the end, it says:

Caution​

After you’ve completed all removal and reassembly steps, learn how to initiate the System Configuration process.
(https://support.apple.com/en-gb/100620)

When I follow the link to System Configuration, it guides me through how to enter Apple Diagnostics—except we’re not running a diagnostics test.

Usually, to run diagnostics online, we have to request it through Apple Support and enter the machine’s serial number. This has to be initiated from another computer, which acts as a control interface for the diagnostic process.

Once requested, online diagnostics will start, and you navigate through the options on the other machine’s web browser.



Hope you’re following me!

Now, back to the repair manual...
It does NOT tell me to do anything online. Instead, it says:
When the Diagnostics & Repair screen appears, click “I agree“ to begin System Configuration.

It looks like Apple is going to open a session for my machine to configure it.

Ironically, you can replace just the Touch ID through the Self Repair Program, but at the Apple Store, they want you to replace the entire logic board as well.

True, I don’t yet know if this is going to work or not.

The Touch ID costs £66.43, and the System Configuration is technically free.

I’ve already ordered the Touch ID for my original "OLD" serial number.
Let’s see what happens.

At this point, I’m more curious than devastated about what has happened so far.

 

[SYS_64738]

I got an email saying the replacement Touch ID was dispatched.

And then it got me thinking—maybe they apply access to the configuration when they dispatch the parts so that later, no human interaction is needed.

So, I ran diagnostics with the old original Touch ID still in the machine.
And yes—after agreeing to the terms and conditions on the diagnostics page, System Configuration started.

But... it was not successful.

The reason could very well be that they scan the serial number of the new Touch ID they dispatch, and the configurator only allows that specific Touch ID to be bound to the logic board.

Now, I just have to wait for it to arrive and install it.

Of course, I’ve used up my one-time access to System Configuration, so I’ll have to contact customer service to get it authorized again.

But it was worth the try! At least now I (we) know that this is a no-go.

 

[SYS_64738]

The new touch ID arrived. A good while ago but and I installed it.
After contacting the support team I was able to run the diagnostic / configuration again.
But even with the new touch ID the configuration still failed.

Well I was very disappointed but not because of the config failed. I have already declared this logic board doomed so it didn't made me mad. I was mad because of the Self Service Repair Store return policy.

So before you start "but you screwed it up why would they accept your return?!". I actually didn't start on saying anything about return but as I was still connected to live chat while I was performing the calibration the agent typed in before I could that she can see the config failed. And she offered a warranty return without I even asking anything.

Initially that sounded like I at least don't loose out on the cost of the touch ID but quicly that turned out to be not correct. She said to be able to process the return request I would have to place a new order for a new touch ID and pay for it. Then with the new order number she would be able to initiate the return for the old one.
I was well surprised on this. If they only do re replacement then why do I have to pay for the new one and wait for the refund on the old one?

But never mind, let's just forget this little hiccup. Well I was kind of lucky because I have paid for the new one and transaction was confirmed I gave her the order number and she sent me a return label for the old one.
I have then posted the touch ID back and the next day and later I got an email from Self Service Repair Store saying there was a problem with the payment and the cancelled my new order.
Sure enough after checking my bank account I confirmed the money never left my account.
So at the end I was able to return the touch ID without paying for a new one.

So I actually left the macbook as is. In pieces. I waited for the refund just to be sure. Then after receiving the money that took quite a while like 3-4 weeks, I finally sat down to put the original touch ID back in there and call it a day.

And that is when I ... you will laugh ... noticed something. And I was like no f**k! The connector on the little sub PCB ro sub logic board how you want to call it so the connector had a tiny leg missing.

Looked it from closer and yep it was gone. So who knows when did that got damaged may be right at the start of the entire story but it may was still present there but bent/broken/non-working.

So I replaced that little pcb with one I purchased from ebay. Put everything together including the original touch ID the machine came with and...
...everything works.

Yep, it was me who screwed it up probably right at the start.
I just didn't see the damage.

Well, it was an experience. 😂🤣😂🤣

 

[Ruggy]

A great story and you deserve credit for seeing it though to the end.
Very frustrating for it being some tiny little thing like that.
You did well to spot it.

 

[SYS_64738]

If anybody is interested what is in a touch ID repair kit from Self Service Repair Store here are some pics: