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yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
MacBook Pro (Retina, 13-inch, Early 2015), has Latest OS, Big Sur, 11.5.2 (20G95), and System Firmware Version: 427.140.8.0.0.



Whenever I try to boot it normally, into recovery mode, Safe mode there is a delay of 2 minutes between pressing the power button and the startup chime and apple logo.

I have tried SMC reset, NVRAM Reset, Setting SSD as startup disk and many more commonly suggested fixes.


I think based on my research, There are some pre-boot tests it performs before the startup chime happens and the Apple logo is displayed, So it might be taking too long to finish those tests. All the parts are original.

I have run apple diagnostics and used various other tools like Disk Utility, Etrecheck, and many more but no issues were found. Further, the MacBook runs fully optimally when it boots up, with No issues whatsoever.

I opened the MacBook a few days ago to clean the fan, that's when the issue started. I have tried removing SDD, Fan, IO Board, Display cable, Battery, and starting the mac but none has managed to kill that 2-minute boot delay before startup chime.



Does anybody have an idea, which issue it might be, and how to fix it?



Regards
 

Audit13

macrumors 604
Apr 19, 2017
6,812
1,810
Toronto, Ontario, Canada
If the issue started after you opened the unit for cleaning, is it possible you knocked a capacitor, resistor, or connector in such a manner that it's causing this delay?

Does this happen if you remove the SSD and boot from an external USB drive?
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
I am pretty sure There was no hardware damage at all. Yes, it still delays when I boot from the external drive, It even delays when I boot to startup manager pressing alt and booting.
Since the delay is before the startup chime, I don't think this is an issue on the SSD side, I think the issue is it is taking long to complete the pre-boot tests, Maybe the firmware became corrupt, But I don't see any option to reset the firmware since it happens with OS upgrade, and I am on latest OS.
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
No I didn't keep the battery disconnected all the time, But I did disconnected and connected it again once.
 

Audit13

macrumors 604
Apr 19, 2017
6,812
1,810
Toronto, Ontario, Canada
Disconnecting and reconnecting the SSD with the battery connected may have caused the problem.

There may be an issue with the firmware but, as you mentioned, the MacBook is already running the latest firmware.

Re-flashing the firmware may not make a difference since the MacBook performs a basic pre-boot search for the hardware components before handing off control to the OS. The pre-boot search may be detecting a hardware flaw which causes the delay.
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
Hmm, Thats a bit fancy for me to perform.
Is there any way we can see the pre boot log files? So I can see the exact error or issue.
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
It doesn't show any errors, and finishes fast as before, So I assume the pre-boot tests are different than the apple hardware tests.
 

Audit13

macrumors 604
Apr 19, 2017
6,812
1,810
Toronto, Ontario, Canada
Even a firmware update may not solve the issue. The firmware update happens when the OS is installed to an internal SSD. If the internal SSD is damaged in some way, the firmware may not update. Even if the firmware does update, it may not solve the pre-boot issue if removing and re-installing the SSD caused a minor short somewhere else on the board.

Did you test all of the MacBook's functions like the camera, microphone, ports, etc.?
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
Yeah all the functions are working, and I can't see any issue in the performance of the macbook at all.
Only the boot delay is the single issue.
 

Audit13

macrumors 604
Apr 19, 2017
6,812
1,810
Toronto, Ontario, Canada
Then I am lost as to why this is happening. Perhaps there is a component that is borderline and takes a few tries before the component(s) pass(es) the diagnostics.

It seems too much of a co-incidence that this started happening after removing the SSD while the battery was connected.
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
Yeah, I am almost lost as well, Last hope is the OS upgrade causing firmware reinstall and it somehow fixing the issue.
 

Audit13

macrumors 604
Apr 19, 2017
6,812
1,810
Toronto, Ontario, Canada
The firmware in a new OS may not completely re-write the existing firmware and may only upgrade parts of the firmware that need to be updated, similar to the UEFI in a PC, whereby not everything is erased and re-written.
 

yogeshbansal

macrumors newbie
Original poster
Sep 7, 2021
15
1
Wow, then I have to live with the boot delay,
I was hoping I could at least get an error code out from the pre-boot tests so that I can be at relief its a hardware or software issue.
Due to the uncertainty Its hard to trust the machine :(
 

adrianlondon

macrumors 603
Nov 28, 2013
5,028
7,597
Switzerland
Might be something useful in this thread:
 
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