[HELP] 820-02020 stuck @5v

[phantomEVO]

i have not kernel panic because motherboard doesn't boot at all!!! i have 5v on usb port!

resistence to ground of pp1v8_s2 is 3k

i have 1,7 not stable on this line

[mon2]

Completely clear that the unit does not boot but if it does - you will face kernel panics due to this defective wifi component and will power cycle at every ~1 minute due to this ghetto wifi design by Apple. More e-waste for the landfill. To halt this cycling you need to have a known good wifi module - according to other techs with the same case.

[phantomEVO]

could you explain me better? you think that the problem is on wifi chip? why?

[mon2]

Sure (in order of the faults):

1) designed by Apple
2) see your post #8 - wifi is heating up and causing the 3v3 rail to power cycle because it is drawing too much current. You removed RD810 to halt this power going to the wifi module to allow for the 3v3 rail to become mostly stable. The ~47 ohms to ground short is gone after this RD810 was removed.
3) this temp fix implies that the wifi is most likely defective. Unless the wifi module can be decapped to inspect the internal components - the entire wifi module should be considered to be defective. For now - do not attempt to decap or remove this wifi module
4) review this thread:

(12) M1 Macbook Pro WiFi Repair : macbookrepair (reddit.com)

5) in summary - this logic board is married to the exact wifi module on your board. If you do manage to get this logic board to power up and boot correctly, the boot process will result in a kernel panic because the factory original wifi is missing (due to the removed RD810 component). The boot process apparently wants to see a working wifi module onboard.

6) The same above thread mentions that you can boot normally if you solder in a known good and working wifi module that does not heat up like yours is doing - this will allow you to boot and backup any data you have onboard. However, the wifi will not function because we do not know (or at least is not public) on how the secret marriage exists between this wifi module and the rest of the flash / nand / whatever widget that holds the secret keys.

So at this time, to me, this logic board is a learning tool only unless the wifi module can be made to be functional. Personally have never seen one of these units in our building.

The link you shared on the wifi case also offers a great explanation of this wifi fault. On an aside, see no reason for Apple to perform this marriage of the wifi module to the flash in secret partitions. etc. other than to force the customer to replace the unit if this part fails.

[mon2]

More aside comments - if I was a betting person (although do play the very fixed stock markets) - the secret serial # is being extracted over the low voltage UART lines that are present on this wifi module. Unless they are making use of a rolling counter for the hash (doubt it), it should be possible to spoof the serial # over these uart lines if using a different but working wifi module.

[phantomEVO]

Sure (in order of the faults):

1) designed by Apple
2) see your post #8 - wifi is heating up and causing the 3v3 rail to power cycle because it is drawing too much current. You removed RD810 to halt this power going to the wifi module to allow for the 3v3 rail to become mostly stable. The ~47 ohms to ground short is gone after this RD810 was removed.
3) this temp fix implies that the wifi is most likely defective. Unless the wifi module can be decapped to inspect the internal components - the entire wifi module should be considered to be defective. For now - do not attempt to decap or remove this wifi module
4) review this thread:

(12) M1 Macbook Pro WiFi Repair : macbookrepair (reddit.com)

5) in summary - this logic board is married to the exact wifi module on your board. If you do manage to get this logic board to power up and boot correctly, the boot process will result in a kernel panic because the factory original wifi is missing (due to the removed RD810 component). The boot process apparently wants to see a working wifi module onboard.

6) The same above thread mentions that you can boot normally if you solder in a known good and working wifi module that does not heat up like yours is doing - this will allow you to boot and backup any data you have onboard. However, the wifi will not function because we do not know (or at least is not public) on how the secret marriage exists between this wifi module and the rest of the flash / nand / whatever widget that holds the secret keys.

So at this time, to me, this logic board is a learning tool only unless the wifi module can be made to be functional. Personally have never seen one of these units in our building.

The link you shared on the wifi case also offers a great explanation of this wifi fault. On an aside, see no reason for Apple to perform this marriage of the wifi module to the flash in secret partitions. etc. other than to force the customer to replace the unit if this part fails.

you are so kind with me!! thank you very much!!


but why are you 100% sure that the problem is on wifi chip? this is the video of what is getting hot...


https://www.dropbox.com/scl/fi/p4q2j...vhcg0pxg1&dl=0

I'VE SEEN THE LINK YOU HAVE POSTED...BUT IN MY CASE THE MOTHERBOARD IS TOTALLY DEAD....

it is not a bootloop problem, but a motherboard TOTALLY DEAD @ 5V

DO YOU THINK THAT cutting traces to wifi, will allow the motherboard to boot? (IN BOOTLOOP?)

[phantomEVO]

i'll do a recap of voltages:

PPBUS_AON 12,2v stable and 3V8_AON 3,7 stable

on u8100

PP1V2_S2 0v floating 1,2
PP3V3_S2_UPC floating 3v/2,5/1,6/0
PP1V8_AON_MPMU 1,7
MPMU_VREF_ADC is 0,020v

on u7700

PP0V72_S2_VDD_LOW 0v
PP1V2_AWAKE_PLL 0v
PP1V8_AON_SPMU 1,7 stable
PP0V855_S2SW_CIO 0v
PP0V805_S1_VDD_FIXED 0v
PP1V2_S2_CIO 0v

[phantomEVO]

What do you think?

[mon2]

Measure the resistance to ground of PP3V3_S2_UPC. No power during these measurements.