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820-00928 Critical Software Update Problem

M

MeTech Turkey

Member
I have a 820-00928 a1707 board bought from ebay to use on my macbook which had an complete trash 820-00281 board. The seller didnt tell me that there is a problem with setup (critical software update problem) and bigger problem is there was water damage on the both edges of the logic board. The computer turns on without any problem and I know that my touch bar was working properly. I have transferred the touch id button also without any problem but I see no signs of touch bar works and it gives me always critical software update problem. I dont know where to start looking at. By the way I dont know if that helps but erasing the SSD was not a problem. Disk utility can erase my SSD without any problem. I have tried both from internet recover and USB recovery but both gave me the same result.
Today I have tried safe mode and I had chance to pass that critical software update problem now backing up with time machine. But I cant see any signs that my touch bar is working or not.
Additional info: It comes to password screen only on safe mode but after I put in my password it comes to black screen and waiting for ages on rainbow spinner but desktop not coming.

Could you please let me know where to start looking at?

Thank you for your help in advance.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Check this thread first:
D

Thread 'Touchbar Critical software update required'

I'm just posting this here for reference as this is a common issue and there are many different causes. This is not about the network error but the error that occurred during installation of the update.

The critical software update is triggered if during normal OSX boot the T1/T2 chip cannot successfully boot BridgeOS that controls the touchbar/touchID/camera/ALS/Dmic.

1 BridgeOS can ONLY be installed on the internal SSD so if the onboard SSD is dead or the lifeboat jumper connector is missing this error will be triggered even if booting from an external USB drive.

2 BridgeOS will also...
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M

MeTech Turkey

Member
Thank you for the link. I went through the thread and tested the suggested possibilities one by one.

So far I have tried:

  • Disconnecting the Touch Bar completely and booting without it.
  • Disconnecting the Touch ID/power button and testing again.
  • Disconnecting the internal display and booting with an external display.
  • Different combinations of the above with the Touch Bar/Touch ID disconnected.
  • Booting from USB recovery as well as Internet Recovery.
Unfortunately, the result is always the same: Critical Software Update Required.

The internal SSD appears to be working normally. Disk Utility detects it and I can erase/format it without any errors.

Since this board had liquid damage on both edges, I am now assuming that I am dealing with a board-level problem related to the T1/BridgeOS initialization rather than one of the external components.

Could you please point me in the right direction regarding what I should check next on the 820-00928 board?

Which power rails, signals or components related to the T1/BridgeOS would you recommend checking first?

I have a multimeter, microscope, schematic and boardview available, so I can perform board-level measurements and component checks.

Thank you for your help.
 
M

MeTech Turkey

Member
Thanks for the clarification.

I checked both J4401 and J4402 in diode mode. Unfortunately, I don't have a known-good 820-00928 board available for comparison, so I used the diode-mode reference values from OpenBoardData.

I found a few noticeable differences:

  • MIPID_CLK_CONN_P: measured 0.527, reference value is approximately 0.780
  • MIPID_CLK_CONN_N: measured 0.527, reference value is approximately 0.780
  • DFR_DIPS_RESET_L: measured 0.507, reference value is approximately 0.710
Both MIPID clock lines give exactly the same 0.527 reading.

I also checked the voltages present at J4401/J4402 and I couldn't find any abnormal or missing voltage. The voltage rails at the connectors appear to be correct.

Since I don't have a good board to verify the diode readings directly, I'm not sure how reliable the OpenBoardData reference values are for this particular board/revision.

Do you think these lower diode readings on MIPID_CLK_CONN_P/N and DFR_DIPS_RESET_L are significant enough to investigate further? If so, should I start tracing these lines toward the T1 side and check the associated components?

Thank you.
 
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