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Luse

macrumors newbie
Original poster
Dec 12, 2015
6
2
Mac Pro Issue
Hello everyone,

First excuse me if I did a poor job using the search and couldn't find a thread where this has already been discussed/fixed. My problem appears to be very similar to this thread

I would try to keep it as simple as I can.

I bought a used 2019 MBP 16”, condition water damaged and no POST (yes, I know how it sounds, yes I know I should’ve bought a one in working condition if I didn’t want the hassle but… the price was really gooood and I rolled the dice).

After getting it, I opened it and there was some visible damage to the touchpad (keyboard?) big cable that goes over the battery, in addition to some small (corrosion /reaction?) on top of one of the cells of the battery (I can upload a pic for those who are interested). The notebook really wasn’t starting at all, but disconnecting the touchpad cable made it boot.
  1. The Touchbar remained dark on the login screen
  2. No trackpad/keyboard
  3. Fans appear to be at max
  4. Battery is absolutely dead (notebook shuts down immediately when the charger is disconnected)
Unfortunately there was an account on it. Here’s where the my current problem starts and I’m hoping someone around here can help.

I booted in recovery and cleared the disk, then proceeded to reinstall MacOS. It didn’t come at all to my mind to check anything else, I was offered to reinstall Big Suhr and just hit next. To my surprise (I wasn’t closely monitoring the installation process) when I came back to the computer, I was greeted with the internet recovery screen. This is pretty much where I’m stuck. I cannot boot an external USB drive (which I created), due to Startup Security Policy. If I boot from Internet Recovery, I’m being stuck into Boot recovery assistant and being asked to “A software update is required to use this startup disk“ ( no disks are visible, except if I plug the flash drive, which is greyed out). After clicking update nothing happens. I cannot boot into regular recovery to try to change the Security policy.

My guess is that somehow the reinstallation of the OS failed, but the disk is either wiped or in unusable state, which deprives me from the regular recovery, so I’m not able to boot into it order to change the Security re Policy and boot to reinstall from USB (if the computer is not locked with find my Mac and I’m screwed) (and I suspect that somehow the security policy is also blocking the internet recovery image)

Any advice on next steps would be greatly appreciated. Obviously, servicing by apple would be last resort (if possible at all, considering that even before looking at the boot issue, they would want to replace everything without the screen which would make the whole endeavour financially unviable).

Sorry for the long post.
 
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chscag

macrumors 601
Feb 17, 2008
4,622
1,946
Fort Worth, Texas
I hope you didn't spend too much on that MBP, because it appears you have a brick. The T2 security is likely broken along with the logic board which means you can't really do anything. And like you stated, taking it to Apple (even if they accepted it for repair) will likely not be cost effective.

I would place it on eBay and try to sell it for parts hoping you could reclaim some of what you paid for it. Perhaps someone else who is experienced in these type of repairs can offer you some better suggestions.
 

Fishrrman

macrumors Penryn
Feb 20, 2009
28,469
12,592
chcscag has "told it like it is".

You bought something that is all-but worthless short of an expensive repair.

You'd best "sell it for parts" (with full disclosure as to its problems).

Then buy something that you KNOW "is good" if you want a working MacBook...
 

Luse

macrumors newbie
Original poster
Dec 12, 2015
6
2
So after some extensive back and forth, including talking with Apple Support, I'm going to write what I've done so far, just in case it's helpful to someone else.

Currently the MacBook is still unusable.

  • It's possible to boot into internet recovery, however it complains about "A Software update is needed to use this startup disk". Dismissing the message leaves you into regular recovery
    • Not possible to disable startup security, as it throws an error message "No Administrators found" after attempting the authentication window
    • Doing the update does nothing (it reboots and reboots and it's back in recovery)
    • Attempting to do the update without a working internet connection fails
  • Following advice from stackexchangeI used my other MacBook to create an installation (not media to install the OS, but actually install it up to the Welcome screen with country selection) on an external drive and attempted to restore it to the internal SSD of the affected machine
    • Big Sur fails, as it complains of "The Source Volume cannot be restored because it has a broken seal" - this has to do something with APFS and Big Sur cryptography, where basically prevents any restore or booting of the volume/drive on a different mac
    • Catalina restores just fine and actually boots for a brief moment (I can see the, gray background and briefly the cursor shows up in the top left corner), before restarting and being greeted with the "A software update is needed to use this startup disk" error again (and it does nothing but boot looping)

So my (amateurish) view is, that the T2 chip either
  • messed up something on the software side during the initial installation of Big Sur the first time around
  • it was prior to that partially damaged / some dependent component is damaged
  • some HW/health/validity check fails due to the disconnected touchpad (keyboard/touchbar?) cable
I would assume that the only remaining thing that I can do is to recover/restore the Mac/T2 via Apple Configurator 2 as explained here . However I haven't been able to boot into DFU mode using a Magic Keyboard (connected with Apple USB-C -> Lighting cable). My suspicion is that the T2 chip would boot to DFU mode only with the build-in keyboard as opposed to the external one (which probably goes through a USB Hub and is connected to the T2 in a different way). Which for me it's not possible due to the disconnected cable.

Just as a FYI, I've been quoted a €750 price for the "top case" as part (keyboard, touchpad, battery) (assuming thunderbolt ports, speakers and motherboard are working), without labor - which would still make it feasible considering that it's a 8core/64g ram config. And I strongly believe that the other components are fine/working condition, considering that it's possible to boot just fine, startup chime is there, connecting peripherals, etc...

Hello maybe you can start a restoration since your latest Time Machine ?

I don't have a time machine backup of that machine, and the closest I have is only a T1 MBP. But thanks.

Read about boot security here https://support.apple.com/en-us/HT208198
You need to enable booting from external drives first
I'm aware of that, as mentioned in the original post, it's not possible to change the setting due to the "No administrator found"
 
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