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Another 820-2936-B EFI Lock question

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  • Another 820-2936-B EFI Lock question

    Macbook was unlocked with another BIOS, serial number edited. ME region not cleaned. Macbook works so far so good. Starts fast and all that. Do I need to clean ME region? Am I not seeing something I should?


  • #2
    Do you have the original backup of the board?

    Sometime "dirty" ME region will work from one board to other.
    But no warranty what can happen in the future...


    • #3
      Yes, I have the original backup.


      • #4
        Then replace ME region and Fsys area with the ones from backup...


        • #5
          If I may ask a small hint/tip/link/direction how to do it? I could just google it I guess, but you guys might have more straight to the point tips.


          • #6
            Intel FITC can extract ME region and then you can change it with any hex editor; I prefer HxD.
            In the same editor, change Fsys area (Fsys <--> $SVS marking strings).

            You can also choose to post your backup here...


            • #7
              Serial number editing of the BIOS will result in its checksum not matching up, however this should resolve itself if apple pushes a BIOS update. The functionality of the device is not impacted by it usually. If it works right now you may keep the BIOS

              Bad or re-used ME region might give issues later and I do recommend to get a clean one.

              I honestly might write a tutorial for this someday because this question gets asked a lot, but here is quickly explained how you do this:

              1. Download MEAnalyzer from:
              2. Dump the SPI flash to file and open this with MEAnalyzer, it will tell what engine version you're using.
              2.1 Download this engine version AND appropriate "ME system tools" from the win-raid website
              3. Unpack the ME system tools and open Flash Image Tool
              3.1 Open the old .ROM in Flash Image Tool and Go to File > Save As and save the current config .xml somewhere (You just need it for the next steps)
              3.2 Close Flash Image Tool after saving
              4. Flash Image Tool has now created an unpacked folder with your BIOS, replace the "Me Region" file with the clean ME Region you've downloaded from win-raid (Make sure the file name is identical!)
              5. Open Flash Image Tool again and load the config .xml (Make sure not to load the .ROM! Just the .xml), this will load the unpacked files with the now new and replaced ME Region
              6. Press Build Image
              7. In the Flash Image Tool folder will now be a new build folder containing a .ROM file that will precicely fit your macbook's SPI ROM. Flash it to the macbook
              8. Enjoy, make sure to run ASD after flashing to verify basic ME workings!

              No idea if this is the best or easiest way but it has worked for me in the past
              Last edited by smiba; 10-14-2018, 09:15 AM.


              • #8
                Correct ME region supposes copy the entire configuration of ME region from the board to a clean ME region.
                You can download (generic) clean ME from Internet repositories, or extract one from a full BIOS update; HP, Acer, Toshiba, even Lenovo serve them (not always).
                This is not easy job at all, as there are many-many settings to modify...
                Need to work with Intel FIT on two ME regions at the same time.
                One step mess and you must restart the job.

                Sometime one board works with "dirty" ME region, flashing complete dump from other board.
                So why shouldn't work with generic clean ME also?
                It will (probably) work, but keep in mind, that is not (100%) correct ME region for that board and nobody can guarantee any issues in time.
                Some ME issues could appear in days, or months.

                Buying dumps from eBay, or downloading from Vinafix, guees what kind of "clean" ME region you'll get...
                On eBay mostly get copied dump from another board; no clean ME at all, nor even generic!


                • smiba
                  smiba commented
                  Editing a comment
                  Given that the ME region on the currently flashed rom came from a same model macbook, FITC will export the configured ME settings to the .xml file. If you replace the ME binary with a "clean" one and loading this XML means the clean ME will be configured with the settings moved over from the original me area. - Atleast, as far as I'm aware. If you can proof me wrong please let me know. I'm always up for learning new things
                  Last edited by smiba; 10-14-2018, 07:02 PM.

              • #9
                I'm back to this post after a while.

                Does someone mind correcting this BIOS file after all? (delete ME Region and Fsys area)

                Here is the link:



                • #10
                  Take it from here
                  It comes directly from dukefawkes; clean ME, PRAM reset and unlocked, based on your backup.


                  • #11
                    Thank you very much. Please mark as solved.


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