A1990 MacBook Pro boot looping

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  • Stephen
    Meow Meow MEOW!
    • Apr 2020
    • 667
    • United States
    #1

    A1990 MacBook Pro boot looping

    Did a T2 restore. Boot loops constantly then eventually loads the OS.

    Did a T2 Restore and revive and OS reinstall. Same issue. Downgraded OS as well nothing.

    No visible water damage seen. No burn chips and MacBook has never been worked on.

    Once the OS is fully loaded seems good. For a while.

    No kernel panic info shows up so definitely curious what’s going on.

    It does boot fully into safe mode without issue.
    sigpic
    MEOWING IN THE IMPOSSIBLE UNIVERSE!
    Tags: None
    • mon2
      Badcaps Legend
      • Dec 2019
      • 13940
      • Canada
      #2
      Re: A1990 MacBook Pro boot looping

      Check each and every SMBUS line.

        Comment

        • smzlwan223
          Member
          • Mar 2022
          • 20
          • 中国
          #3
          Re: A1990 MacBook Pro boot looping

          205/2000
          Good News and bad news! This kind of problem in my past maintenance experience, encountered a lot of similar models of similar failures, are a problem, CPU bad, BAD CPU! BGA CPU replacement perfect solution! If the appearance of the test, no problem, other measurements, are redundant!

            Comment

            • mon2
              Badcaps Legend
              • Dec 2019
              • 13940
              • Canada
              #4
              Re: A1990 MacBook Pro boot looping

              Good to know. From where do you source a replacement CPU? Donor board or can you share the details of a good vendor with reballed CPUs?

                Comment

                • smzlwan223
                  Member
                  • Mar 2022
                  • 20
                  • 中国
                  #5
                  Re: A1990 MacBook Pro boot looping

                  We generally recycle chips from customers who scrap their motherboards, but we also get them from our peers. Buying them online requires a certain element of luck, which involves, sellers and buyers, IC dismantling, manual problems, and temperature control, if you don't handle it well, it will break!

                    Comment

                    • Stephen
                      Meow Meow MEOW!
                      • Apr 2020
                      • 667
                      • United States
                      #6
                      Re: A1990 MacBook Pro boot looping

                      Sigh it’s a i9 32GB board. Sucks this is a bad CPU or GPU.
                      sigpic
                      MEOWING IN THE IMPOSSIBLE UNIVERSE!

                        Comment

                        • smzlwan223
                          Member
                          • Mar 2022
                          • 20
                          • 中国
                          #7
                          Re: A1990 MacBook Pro boot looping

                          There is another solution to this problem, which is to modify the circuitry, to solve the reboot problem, but the researchers have not yet published this solution, and friends around me have learned that it is partially solved by modifying the temperature control, you can go into safe mode, view the system error log, find the corresponding point to modify the circuit! You can try... !

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