MacBook Pro 2019 A2141 820-01700 NAND Issue Stuck in DFU

[fusioninfo]

MacBook Pro 2019 A2141 820-01700 NAND Issue Stuck in DFU

Ok, here's an issue ive got on a A2141 820-01700 MBP 16' 2019. No signs of life, 5.06v 0.0a on usb-c meter, on each 4 usb-c ports.

Nand voltages are missing.

I've found no shorts at all so far, no signs of heat via thermal camera either.

PPBUS_G3H 12.31
PP3V3_G3H_RTC 3.387v
PP3V3_G3H 12.31v
PP2v5_NAND_SSD0 0v 58 ohms
PP2v5_NAND_SSD1 0v 57.8 ohms
PP1v8_SLPS2R 1.8v
PP1v1_SLPS2R 1.1v
P3V3_G3H_SOCPMU 3.37v
PP0V9_SLPDDR 0.9v

P3v3_UPC_XA LDO 3.3v
PP3v3_UPC_XB_LDO 3.3v
PP3v3_UPC_TA_LDO 3.3v
PP3v3_UPC_TB_LDO 3.3v

Tried revive and restore via apple configurator, fails every time with 4014. Device is detected in DFU mode without me forcing it, booting into it by itself, but i've noticed P2v5_NAND_SSD0/P2v5_NAND_SSD0 ramping up to 2.5v 1 second when trying restore/revive, then back to zero. So it's trying to power on the NANDS, but shutting them off after.

Anyone has an idea at this point ? Thanks.

 

[2informaticos]

"PP2v5_NAND_SSD0 0v 58 ohms
PP2v5_NAND_SSD1 0v 57.8 ohm"
Too low resistance.
Compare with good board, or refference table.

OpenBoardData Project

One or more NAND chips damaged.

 

[fusioninfo]

Ok idk how i did this, but i messed up with the measurements.

I retook diode mode for these, here's the results :

PP2v5_NAND_SSD0 0.390
PP2v5_NAND_SSD1 0.413
PP1V8_SSD0 0.348
PP1V8_SSD1 0.403

 

[2informaticos]

Check all secondary power supplies for short.
Be sure to use 96/140W charger and connect battery too.

 

[fusioninfo]

Which lines exactly ? Not that much experience with these. Thanks

 

[fusioninfo]

The power supply i have is a 3rd party 96w PSU, not apple original.

 

[2informaticos]

Many lines; check pages 69-79.

 

[fusioninfo]

Sorry, what pages are you refering to ?

 

[2informaticos]

The 10 pages above mentioned; with the secondary power supplies...

 

[fusioninfo]

I don't understand how you determine pages in a website document ? Might be a stupid question, but i don't understand.

 

[fusioninfo]

These : ?

[nMU_CLK32K_SOC]
[nP1V8_AWAKE]
[nP1V8_SLPS2R_PMUGPIO]
[nP1V1_SLPS2R]
[nP0V8_SLPS2R]
[nP0V82_SLPDDR]
[nP3V3_AWAKE]
[nPVDDCPUSRAM_AWAKE]
[nP0V9_SLPDDR]
[nP1V1_SLPDDR_SOCFET_EN]
[nP1V1_SLPDDR]
[n:H9M_24MHz_CLK]
[nP1V2_AWAKE]
[nPVDDCPU_AWAKE]
[nMU_SYS_ALIVE]
[nMU_ACTIVE_READY]
[nMU_COLD_RESET_L]

 

[2informaticos]

I was talking about power rails, not signals.
SLPS2R and AWAKE signals should be always present and stable.
In this case is more important to check on the big coils and after the power FETs.

 

[fusioninfo]

Sorry i'm a little lost at this part, i don't know what to check exactly.

 

[2informaticos]

Each of mentioned page has one or more secondary power supply detailed.
You must check every one for short on its output.
Some of them may have an output voltage pulse (if no short).

For the big power supplies, you can check on their output coils (pages 70-73 and 78).
U7800 has several small coils to check (page 75); but also need to check its LDOs (page 76).
Some power rails are available after switching circuits on page 79 (Power FETs page).