Apple MacBook 12'' Retina A1534, MB: 820-00045-A, Flashing folder on screen

*********************************************
Brand: Apple
Model: MacBook Retina A1534
Motherboard: Apple Inc. 820-00045-A
Schematic: J92 MLB (Sch. part number: 051-00107)
*********************************************
Hello!
I'm working on the mentioned laptop.

Issue:
- When I turn it on, the flashing folder appears on the screen (picture below). It won't boot, the Apple logo does not appear.


As I know, this means that the operating system can not be found.

What I've done up to now:
- Reset it by removing the main battery -> no changes.
- Enter the "Recovery Mode" with "Command" + "R" key combinations -> error "-1005F" (picture below).


I think that, the issue is related with an SSD drive, which is probably not detected. In this model, the SSD drive is unfortunately integrated on the motherboard.

Pictures of the motherboard:


There are two SSD drive chips on the motherboard "U8801" and "U8810" (both are under the metal shield).

The new motherboard is very expensive, so I want to repair the old one.
A person, who will contribute to solving the issue, will receive a 100 points reward.

Vogelek23 hat geschrieben:Firstly, please try to boot this machine from an external drive.

This machine has only one connector (except headphone jack) - USB type c. If I understood you correctly, I need to use for example a USB type c flash drive with installed MacOS?

I bought a dual USB flash drive (USB type-A + USB type-C) and create a bootable MacOS "High Sierra 10.13" on it.


I plugged the USB flash drive into the machine, pressed the power button and then held the "Option" key. I got the screen on the following picture:
after 20 seconds appears the following screen:


I tried with both (left and right) "Option" keys, but it is always the same.

Yesterday I managed to get the right screen once (picture below), but then I shut down the machine, because it was late.


If I connect the charger to USB type-C the battery charges normally (battery bar appears on the screen) and then machine turn itself on to the blinking folder on the screen.

Any idea, what I'm doing wrong?

I tried everything, but I'm not able to get the "Boot-up" screen again .

I tried to turn on the machine and then held down the "Alt" key ~30 times (also with and without re-plugging the USB drive), but it is always the same - just the "Internet Recovery" screen.

I also tried to:
- Reset the SMC.
- Remove the battery.
- Format the USB drive and create the bootable "MacOS" again.

I have no idea, how I got it once before

SebastianR hat geschrieben:Maybe this is related somehow with keyboard issue? Have You tried booting the machine with external keyboard connected?

This machine has only one USB type-C connector, so it is impossible to connect the USB flash drive + external keyboard at the same time.
I'm 99.9% sure, this is not the keyboard related issue.

czaki00 hat geschrieben:Try different usb C device, if you got another Mac you can install fully functional OS on USB C pen.

Unfortunately I don't have another USB type-C flash drive. I also don't have another working Mac.

Vogelek23 hat geschrieben:Did you perform a PRAM reset (Alt+Cmd+P+R immediately after switching on)?

Yes, it does not change anything.

Vogelek23 hat geschrieben:Did you try to call AHT (Alt+D)?

It throws a "-1005F" error as well.

Vogelek23 hat geschrieben:You may receive an error like "-1005F" because you have unplugged battery and the date and time have been reset.

I got the same error before disassembling it.
This machine was previously at another repair shop, where they said that the motherboard is bad and it need to be replaced.
According to this, I'm probably not the first one, which unplugged the battery.

I bought an USB HUB (exactly the same as on your picture):

Vogelek23 hat geschrieben:the best way is to purchase a standard USB 8/16GB flash drive + USB-C to USB adapter/hub (like the one shown below). Then, you can put a macOS High Sierra offline installer onto a flash drive.

I created a bootable MacOS High Sierra 10.13 on standard USB 2.0 flash drive and connect it to the USB HUB.
Now I get the following screen without problems.


I run the "Disk Utility" now. I assume that, the internal SSD drive is not detected (screen picture below).


What to do now?

Vogelek23 hat geschrieben:Check the voltage on L7561, L7890, C7872, U8999 (VOUT), U7870 (VOUT), U8901 (S output), U8902 (S output), U8903 (S output) and U8920 (S output).

All voltages seems ok:
L7561= 3.30V
L7890= 1.11V
C7872= 2.50V
U8999 (VOUT)= 3.30V
U7870 (VOUT)= 2.50V
U8901 (S)= 1.20V
U8902 (S)= 1.80V
U8903 (S)= 1.80V
U8920 (S)= 1.20V

Vogelek23 hat geschrieben:If all voltages are present, you may need to reflash U8800 (it is very important what the NAND chip model is assembled onto the motherboard - please check page 54 of schematic for more details)

Is there any other option to check the NAND chips model except to read the markings from the chips itself? Both NAND chips are namely located under the metal shield, which I don't want to remove and risk the damaging of the motherboard if it is not necessary.
The customer has the original documents from this machine, according to which it is 256GB model.

Try Reflow nand first, before you removed .

I didn't intend to remove the NAND chip, but only the metal shield to view the NAND chip markings.

Basicly for MB like this and problem what you have I use reflow bga owen. Possibility the problem is not nand but CPU that have only small heatsink and that's it.

Before the reflows I would like to exclude the other possible "suspects". The reflow is the last option, because as I said I don't want to risk damaging the motherboard if it is not necessary.

I tried to flash the EFI chip via "ISP", so I soldered the ISP wires to the motherboard, but my programmer won't detect the chip.
I noticed that, the EFI chip power supply (power rail PP3V3_S5) is missing, when the laptop is turned off. It appears after pressing to the power button.

As I know the flashing an EFI chip, while the laptop is turned on is not a good idea.
Any idea how to flash the EFI chip via "ISP"?

I'm still working on this laptop...

I noticed that the EFI chip power supply (power rail PP3V3_S5) in standby is present, when the battery is connected. With power supply only this power supply is not present.
I tried to flash the EFI chip again, but my programmer still does not detect it. I checked the connections of ISP wires twice, the EFI chip power supply is present now.

EFI chip:


In programmer software I selected the chip Winbond W25Q64FV and I get the following table of connection the ISP wires:


I connected the ISP wires to the following signals of the motherboard:
ISP1 (SDO) -> SPI_MLB_MOSI
ISP3 (/CS) -> SPI_MLBROM_CS_L
ISP5 (SCK) -> SPI_MLB_CLK
ISP7 (SDI) -> SPI_MLB_MISO
ISP10 (GND) -> GND



As I said, my programmer still does not detect the EFI chip.

******************************************************************************

Once, when I turned on the laptop to "BOOT" mode I noticed that the main SSD hard drive is detected:


That happened only once.
Do I still have to deal with the EFI chip flashing, or I need to do something else in the light of the above?