MacBook Pro 16" 2019 A2141 Issue (powers on)

[Stephen]

Board powers on, holds charge it seems, track pad clicks, display is working etc. When trying to boot it turns itself off and then boots again and repeats. If it stays at GLOBE icon it will not turn off. Customer needs data, enabled THUNDERBOLT Mode, plugged in Thunderbolt cable, but error comes "THIS DISK CANNONT BE UNLOCKED DUE TO AN ERROR" I can't even input a password. Did a soft restore to retain data to see if it will solve any firmware issues. Nothing, I do not want to restore the computer because the customer needs the data, computer stays on completely when at Globe or Thunderbolt mode, does not turn off, however when you try to load the recovery or even DIAGNOSTIC MODE it will boot loop and turn off and turn itself on. I unplugged the computer to see if the battery is the issue since the batteries are the culprit for this stupid issues, sadly computer stays on with computer unplugged so assuming the battery is fine but not completely ruling that out. I have a used battery that works so I will go that route if that is the case. But would like an opinion on this matter. Also Safe Mode does not work either, I also tried Recovery mode to see if I can reinstall the OS but it won't even load. Thanks!

[mon2]

Same crap ware from about a week or 2 ago. You are using the Target mode? Is your host on Sonoma? We used another a2141 to save the data.

[Stephen]

Different computer. We have about 20 computers we are working on. Just backed up. So you're saying host computer needs to be on Sonoma? And yes using Target disk mode in Thunderbolt. It doesn’t turn off when in this mode

[mon2]

Sorry - meant to say that we had the same model in the shop and the client really needed the data off the unit. We were about to send it off to Master Liu in Shenzhen but with the feedback from this forum, used target mode to extract the same vital data.

For us, we attempted to use an a1534 as the host and while we could see the logon screen and the hint for the password, the process failed. Then we decided to purchase a known good but used A2141 so that the OS was matched (Sonoma). This combination worked for us using a quality 40G rated USB / TBT cable from Amazon. After the same password use, saw the SSD drive on the desktop and the client was able to back it up. We actually used the migration process and he purchased the cloned but working 2nd unit.

The target mode is amazing and must be an early stage bootloader so that it does not care about the tail end of the non-working boot process.

Do you have a logon screen? Is the password 100% the correct password? If available, test with the higher OS version box you have in the building.

[Stephen]

No login screen. We hook up the customers computer to another A2141 and it sees the drive in Target mode. The computer will not load the OS and will boot loop. Thought it would be the battery but it holds a charge and stays on while off power. It doesn't boot loop in target mode but we get the error Disk cannot be unlocked.

however I have about 10 A2141 in stock so I’m going to update one to SONOMA and see if that helps.

[Stephen]

On Sonoma now, this is the message I am getting.

[mon2]

https://apple.stackexchange.com/ques...nt-be-unlocked

[Stephen]

None of this works, the computer won't even go into internet recovery it will just restart, and I do not have the options for this issue. It seems when internet recovery fully downloads and the computer is about to launch it turns off and restarts into internet recovery again. I am certain a DFU restore may solve all these issues but sadly we cannot go this route since the customer wants their DATA. Even if I try to do safe mode and hold shift, it just restarts all the time. It won't post. It refuses to go further. I think this may be a lost cause for their data.

[mon2]

DFU has 2 options: REVIVE and RESTORE. DO NOT SELECT RESTORE = will wipe your data. Select REVIVE to rebuild the corrupt part of the nand flash. Do google to confirm what I am preaching here but that is what we did. Currently busy fixing an air leak on our SMT printer - need to find air quick connectors in the building...SMT line is down.

[Stephen]

Yeah I did a DFU Revive to rebuild the NAND flash but nothing. I am sadly to believe a restore is the only option at this point.

[mon2]

Our SMT printer is fixed and quiet once again

I recall that our A2141 performed a bunch of steps and remember 4/4 phase completed. Do you get any notification of the DFU process (REVIVE only) ? Some articles note that this may mean that your T2 is defective or not working. What is the PPBUS_G3h voltage (or whatever the net name is on this logic board)? It should be 12v6 if T2 has booted.

Master Liu (and others) also noted that if the T2 and NAND are operational - you can get the data off the machine.

What is the nand rail voltage? Measure with care.

[Stephen]

DFU revive was successful but computer refuses to post, just boot looping
Long day, I will open up the board tomorrow and get SSD nand voltage readings.

I am assuming since DFU revive was successful and no error, the T2 is good and the Nand may be good?

[mon2]

Yes, if DFU completed -> NAND is ok. It sounds the same as what we faced but the original unit is still boot looping. Powers on -> fan spin -> chimes -> reboots after a few seconds. We do not reach the login screen and cannot toggle the keycaps led. BUT, we were able to extract the data using TARGET mode on this box. Based on your shared info and your pix, I think the fault is with the T2 itself. Check the voltages linked to T2. Do check if you are at 12v6 on the PPBUS_G3H.

[Stephen]

How would we do Target mode? I use T to boot up the normal mode and use a thunderbolt cable but the board kicks me out with errors. I’m assuming I have to get the T2. Chip repaired 😑

[anhbanxoi]

On Sonoma now, this is the message I am getting.

Try to boot your right laptop to recovery mode and try again.

[Stephen]

Try to boot your right laptop to recovery mode and try again.

Tried that same error "DISK cannot be unlocked"

[mon2]

T to boot up the normal mode = Target mode. You will know if you are in this mode when the macbook shows the Thunderbolt symbol.

reference:
Transfer files between two Mac computers using target disk mode - Apple Support (CA)

I think that the issue is linked to T2 but it is positive that DFU revive mode worked for you. As a suggestion, consider to join the Rossmann tech forum for a month and lean on @2informaticos for advice. Then post the details here. To me, you are in new territory.

[Stephen]

T to boot up the normal mode = Target mode. You will know if you are in this mode when the macbook shows the Thunderbolt symbol.

reference:
Transfer files between two Mac computers using target disk mode - Apple Support (CA)

I think that the issue is linked to T2 but it is positive that DFU revive mode worked for you. As a suggestion, consider to join the Rossmann tech forum for a month and lean on @2informaticos for advice. Then post the details here. To me, you are in new territory.

I will register and ask him. Thanks for the advice, I should be on both forums now haha