MacBook Air Core i5 1.4 13 (Early 2014) problems


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2 years 7 months ago - 2 years 7 months ago #4958 by Kawa
Hi forum,
I dumped the fw and modified it according to the tutorial, but after reflashing the chip, the machine won't start. Fan spins up, then spins down in about 10 seconds, then the cycle repeats endlessly. No chime, nothing on the screen. Tried several key combinations (various reset). Nothing works. I attached the original dump, the modified dump, then the dump for this model found in repo, and the modified repo dump. Could anyone look into them if they are modified as they should? I might have missed something.
Attachments:
Last edit: 2 years 7 months ago by Kawa.

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2 years 7 months ago #4961 by Icecool67
Hi, did you remove the efi ic o you just programmed on board ?

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2 years 7 months ago #4964 by Kawa

Icecool67 wrote: Hi, did you remove the efi ic o you just programmed on board ?


No, programmed on board with the adapter, w/ and /wout battery connected and w/ and /wout power adapter connected.

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2 years 7 months ago #4969 by reverendalc
What was your SPI speed?
Did you pull multiple reads, match their checksum, and verify against the chip?

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2 years 7 months ago #4981 by Kawa

reverendalc wrote: What was your SPI speed?
Did you pull multiple reads, match their checksum, and verify against the chip?


I've read it with Postal3 programmer, I think the default is 100KHz. Multiple reads no, verify yes, both at writing and reading.

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2 years 7 months ago #4996 by reverendalc
Your programmer, is it capable of 3.3v?

Most IC programmers I've seen only do 1.8v. If your power was too low, then the original read was bad.

Always read the chip several times and compare their md5 checksums.

If you flash back the original read, will the MacBook boot?

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2 years 7 months ago #5002 by Kawa

reverendalc wrote: Your programmer, is it capable of 3.3v?

Most IC programmers I've seen only do 1.8v. If your power was too low, then the original read was bad.

Always read the chip several times and compare their md5 checksums.

If you flash back the original read, will the MacBook boot?


Yes, it is, I even hooked up an oscilloscope to see if it drops voltage during reading/writing. Lowest drop was 3.23V. Laptop battery was disconnected during the read and write. Lesson definitely learned regarding multiple reads. I tried to flash back the original read, it doesn't boot, no chime, no video. :(

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2 years 7 months ago #5004 by reverendalc
That's ok, all is not yet lost.

Do we have a copy of the firmware in the repo?

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2 years 7 months ago #5007 by Kawa

reverendalc wrote: That's ok, all is not yet lost.

Do we have a copy of the firmware in the repo?


Yes, I attached the downloaded original from repo, and the modified one with my own serial number in it, in the first post of the thread.

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2 years 7 months ago #5008 by reverendalc
I am at work and unable to inspect your ROM on my phone, but have you tried cleaning the ME region of the repo copy and write that?

That should in the very least get you a chime. If not, we seem to have a communication problem with the chip.

Which chip do you have? Does your programmer identify the flash chip correctly?

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2 years 7 months ago #5009 by Kawa

reverendalc wrote: I am at work and unable to inspect your ROM on my phone, but have you tried cleaning the ME region of the repo copy and write that?

That should in the very least get you a chime. If not, we seem to have a communication problem with the chip.

Which chip do you have? Does your programmer identify the flash chip correctly?


Didn't know about ME region. The programmer has identified the chip as being MX25L6405, which should be for this model. Since we talked I went the RPi route, chip also identified as the above mentioned one.

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2 years 7 months ago #5012 by reverendalc
Ok that's good. There's a blog on here about cleaning the ME region. Try that.

Also, try dumping with the rbp three times and comparing their checksum.

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2 years 7 months ago #5055 by Kawa

reverendalc wrote: Ok that's good. There's a blog on here about cleaning the ME region. Try that.

Also, try dumping with the rbp three times and comparing their checksum.


Well, found that blog, the MEA Analyzer link is dead, found it on GitHub, it's a python script, I installed the missing libs, tried to run that file against the original dump, but that python script is so full of errors that I couldn't get it to work. So basically I don't know which file to download. Tried to identify it by trying to find the chipset using various "serial number decoding" sites. None of them had the info I was interested in. Is there any similar tool that I can use?

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2 years 7 months ago #5063 by reverendalc
I'll have to look into it when I get home, but just a thought:

The Apple download page for EFI updates...

Perhaps a google search of the EFI version might yield some info about the ME?

Also, in the comments section of the ME blog, king bone crusher posted a neat idea worth trying. You could try it with various ME regions, or even experiment adding them to your dump. Just be sure to keep a backup of the original (-:

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2 years 7 months ago #5082 by Kawa

reverendalc wrote: I'll have to look into it when I get home, but just a thought:

The Apple download page for EFI updates...

Perhaps a google search of the EFI version might yield some info about the ME?

Also, in the comments section of the ME blog, king bone crusher posted a neat idea worth trying. You could try it with various ME regions, or even experiment adding them to your dump. Just be sure to keep a backup of the original (-:


Well, that road took me nowhere near to my goal :( Had a hard time unpacking a dmg on linux, but eventually I did, but found nothing that I can use in my case. I do not have another mac. I'm not sure trying different ME regions is such a good idea, considering you interact with hardware almost directly, it could really mess up things. I remember one time when rewrote a firmware in a piece of hardware which had a smart charging based on PWM, few chips blew up because of incorrect values.

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2 years 7 months ago #5089 by TNJed
There isn't any chance you changed the RAM module(s) while you had it open is there? Just ask, because I've had instances where a MBP would exhibit the symptoms you site when it wasn't happy with specific SODIMMs used in an upgrade for whatever reason.

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2 years 7 months ago #5090 by reverendalc
It's very difficult and requires advanced reworking skills to remove ram chips on MBA as they're soldered to the mainboard.

Not very likely lol.

I apologize if I've already asked, but can you provide your board model no and I'll see what I can scrape together?

It's 820-XXXX.

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2 years 7 months ago #5091 by TNJed

reverendalc wrote: It's very difficult and requires advanced reworking skills to remove ram chips on MBA as they're soldered to the mainboard.

Not very likely lol.

I apologize if I've already asked, but can you provide your board model no and I'll see what I can scrape together?

It's 820-XXXX.


My bad, the post title states MacBook Air and I was thinking older MacBook Pro (MBP). Guess it helps to read and think before posting. Didn't mean to create confusion.

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2 years 7 months ago #5092 by reverendalc

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2 years 7 months ago #5094 by Kawa

reverendalc wrote: It's very difficult and requires advanced reworking skills to remove ram chips on MBA as they're soldered to the mainboard.

Not very likely lol.

I apologize if I've already asked, but can you provide your board model no and I'll see what I can scrape together?

It's 820-XXXX.


Where should I find that? I've looked all over the motherboard, couldn't find anything that resembles that. The serial number check didn't yielded anything like that also.

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