A2141 820-01700 5v 0.200 amp draw

[iMuhtaseb]

This computer had an SSD failure initially and I've replaced all NANDs with known-goods and made huge stress tests on the SSDs and on the computer.. then I sold it..

Now after two months of selling the laptop it retuned on 5v and drawing 0.200 amps.. T2 is heating up and U6960..

T2 PMU has all voltage power outputs also U6960 is producing PP3v3_G3H normally..

All USB-C doing the same behavior no USB-C port behaving differently all taking 5v 0.200 amps..

I took measurements for shorts all around and found nothing..

Board is not in DFU and does not go into DFU..

PPBUS 12.3v
3v3 and 1.5 USB-C LDOs reading OK in diode and volt
NAND voltages are not present

One thing I'm not certain of is I found flux around U2800.. I'm not 100% sure if its a residue from me from the first though I highly suspect that because I've cleaned the board of course before selling the laptop.. what's making me even more sus is I found few tiny corroded capacitors around U2800.. and I'm 100% sure this computer did not have liquid damage AT ALL when I replaced the NANDs first time.. it was a matter of dust around the U9580 as always..

They could have sent it to somebody who tried cleaning it up before returning it to me..

But those tiny caps are driving me crazy.. are these corroded caps or am I blind? (I will post pictures when I get back to work today is my day off)..

Anyway back the main issue.. what could be my problem on this board?

Thanks

[mon2]

NAND voltages are not present

What is the resistance to ground for the NAND voltage rail? Review the local regulator and the NAND flash ICs for defects.

The NAND must be powered and work for the DFU to work.

[ GUIDE ] DEAD SSD Issue on 16-inch MacBook Pro ( Fix A2141 2019 ) - YouTube

[iMuhtaseb]

PP2V5_NAND_SSD0 around 45 kilo ohms, diode 0.403
PP1V8_SSD0 around 55 kilo ohms, diode 0.364
PP0V9_SSD0 107 ohms, diode 0.382


PP2V5_NAND_SSD1 around 6 million ohms, diode 0. 418
PP1V8_SSD1 around 54 kilo ohms, diode 0.397
PP0V9_SSD1 168 ohms, diode 0.444

I posted the corroded caps that caught my attention.. pics below

[iMuhtaseb]

Correction: the USB-C controllers U3100 and U3200 are consuming 5v 0.200-0.300 like the others but they are cycling.. UB300 and UB400 are not cycling..

[mon2]

UB300 and UB400 are not cycling.

voltage? Current draw if using these ace controllers?

Each ace controller must function before the board will switch to 20v.

check that each LDO rail is working for each ace controller.

Reference reading:

https://logi.wiki/index.php/CD3215_Bootup_Sequence

[iMuhtaseb]

LDOs were OK as I mentioned in my first post.. It's a CD3217 no 3215.. it has only two LDOs 3.3 and 1.5 and both OK on all USB-Cs..

I've taken diode measurements around the U3100 and U3200 because the corroded looking caps are in that area.. I've found very low diode reading on R3019.. it should read 0.571 and it's reading 0.063

R3019 side 1: 0.063
R3019 side 2: 0.088

Walking down the lines it goes to the TBT ROM..

TBT_X_ROM_WP_L
TBT_X_SPI_MISO

Are reading very low diode readings too

I found UPC_X_SPI_CS_L completely shorted to ground and this line goes to the thunderbolt chip (U2800)

I am certain now that the thunderbolt chip is bad and it's been water damaged and tempered with.. I wanted to go all the way through to be as just as possible.

[iMuhtaseb]

Can I put a U2800 from another device normally or do I need to transfer TBT ROM alongside with it? I looked in my donor drawer and found an exact replacement

T803A900
JHL7540

[iMuhtaseb]

I've a replacement U2800 to the board.. now it's switching to 20V consuming 0.02-0.13 amps.. heat coming from T2 nothing else..
I thought it needs its TBT ROM.. so I also moved it..
I thought it needs revive; failed on error 9
Tried restore; failed on error 9 as well; I tried multiple times to restore..

SSD1 and SSD0 rails volts are all coming in..

PPBUS_G3H was 12.2 now its 12.6
PP3v3_G3H present
PP5V_G3S present
PP1V8_G3S
PP5V_S5_LDO present
PP3v3_S5 not present

PP1V8_AWAKE present
PP1V1_SLPS2R present
PP0V8_SLPS2R present
PP0V82_SLPDDRR present
PP3V3_AWAKE present
PPVDDCPUSRAM_AWAKE present
PP0V9_SLPDDRR present
PP1V1_SLPDDR present
PP1V2_AWAKE present
PPVDDCPU_AWAKE present
PMU_SYS_ALIVE present
PMU_ACTIVE_READY present
PMU_ONOFF_L present

did not find any short on 3v3_S5 or

[mon2]

PPBUS_G3H was 12.2 now its 12.6

T2 has booted.

Is your DFU cabling known good? Using the latest AC2 and OS on the host computer?

[iMuhtaseb]

Yes they are. But ill try different cables and computers tomorrow.

[iMuhtaseb]

On my main host computer it remains on "Installing System" on AC2 then it errors out on 9..
Tried another A2337 machine with Finder (not AC2) to see if anything changes.. the loading bar remains on "Waiting for Mac" then errors out on 9 as well..

[mon2]

Are you attempting to enter DFU with keyboard pressing or logic board shorting pads?

[iMuhtaseb]

I'm using the keyboard method

[mon2]

Perhaps you are not in DFU mode? Can you attempt with the pad short instead?

[iMuhtaseb]

I will try the pads method.. but since AC2 shows me "DFU" on the device list it should be in DFU no?

[mon2]

Then you are ok. Rossmann threads note the fault to be NAND related. Have you seen that thread? Will link it once I am at the office.

[iMuhtaseb]

The ones in repair.wiki? Yeah I’ve read them.. guess i will reball the SSDs since idk what the previous tech did to the board

[mon2]

Have you seen these videos? They are a must watch.

How most 16" Macbook Pros often kill themselves & why they're unfixable (youtube.com)

(1) [ GUIDE ] DEAD SSD Issue on 16-inch MacBook Pro ( Fix A2141 2019 ) - YouTube