MacbookPro 15 A1398 820-3332-A , no start, stops at post code 29

Hello to everyone, they gave me this MacbokoPro saying that they shutted down one day and then the next day it didn't start anymore.
The only thing the machine does is to give tensions to all power supplies but gives back only a black screen, no gong and no 3 ram beeps, CPU and GPU heat up and after a couple of minutes the fan grows slowly to the max.
There are no liquid traces, nor in the outer case nor on the board itself, nor on the edges of the board.
No scratches on main bgas, CPU, GPU and PCH.
I don't have at the moment an original 85W Apple charger, but this one works good with another same A1398 820-3332 Macbook and charges the battery on the not-working Macbook.
If it was for the not-original charger, I suppose it would not even attempt to start to S0 states, would it?
Strange thing is that even if the battery is connected and charged, as soon as the magsafe is connected it starts automatically, every time you disconnect and reconnect it.

SMC bypass is working (keep pushing SMC_ONOFF_L for 5 seconds, connect the charger, release the button and then pushing it again): fan start immediately at the max speed but same things happen, black screen and no starting sounds.
U6100 chip was analyzed, even all resistors around it, they all have correct values and were re-soldered to make sure they have a good contact with the traces on the board, and they have continuity to PCH and SMC respectively, when the board "starts" you can observe CS# going low for a split second, and MOSI (5) and CLK (6) changin values, but I have no oscilloscope to make accurate measures.
BIOS was read by external programmer, verified it had no strange composition or corruption and compared to one extracted from another working 820-3332 board, I even cleared ME region to make sure nothing was wrong, and loaded directly the other bios file (changing its serial) but again nothing changed.

Knowing the classic problem of this board to be U8900 solderings, I have unsoldered it and soldered it back with SnPb tin, the same thing I did to U7400, and noted that also U2600 had very bad solderings, so I soldered it back in the same way, but nothing changed(CPUIMVP_PGOOD = 3.28 , CPUIMVP_AXG_PGOOD = 0.00 , GPUVCORE_PGOOD 3.27).

I can't measure current absorption changes from charger, but I note that PPVCORE_S0_CPU rises to 1.09v and stays there, no other voltage changes, instead on the working 820-3332 board, voltage starts from 1.09 then goes quickly to 1.60 then 0.9, then oscillates around these values.
On PPVCORE_GPU happens the same thing, starts at 0.88-0.89v and no other voltage changes.
PPVCORE_S0_AXG is always 0, as it should be on this board at startup times.

Seems like something can't be initialized after all power rails are on (the board seems to go in S0), seems like CPU is dead, but if I connect a wired optical mouse I can see the red light coming up and a very quick blink in less than 1 second, that should mean that USB controller has been initialized by CPU, so that CPU has read BIOS chip content...shouldn't?
POST card soldered on the main board starts rolling codes for about 2seconds, something like 06-06-29 and stops there.

Here are some measures to note (1st value is resistance to GND, 2nd is voltage after autostart):

PPDCIN - / 19.69
PPBUS_G3H - 403 12.31
PP3V42_G3H - 277 3.35
PPVRTC_G3H - 414 3.28
PP5V_S5 - 430 4.95
PP5V_S4 - 382 4.95
PM_SLP_S4_L - 484 3.28
PM_SLP_S3_L - 493 3.27

SMC_RESET_L - 486 3.31
SMC_ONOFF_L - 675 3.34
SMC_BC_ACOK - 470 3.19
SMC_ADAPTER_EN - 548 3.34
SMC_PM_G2_EN - 519 3.34
S5_PWRGD - 564 3.31
PM_PCH_PWROK - 650 3.31
PM_PCH_SYS_PWROK - 742 3.28
PM_SYSRST_L - 606 3.27
PCH_DSWVRMEN - 792 3.05
PM_DSW_PWRGD - 746 3.34
PM_PWRBTN_L - 527 3.34
PM_RSMRST_L - 627 3.23
PM_BATLOW_L - 531 3.27

PP3V3_S5_AVREF_SMC - 590 3.23
PP3V3_S5_SMC_VDDA - 280 3.35
P1V2_S5_SMC_VDDC - 482 1.18

PLT_RESET_L - 509 3.28

PPVCORE_S0_AXG_REG - 1.1 0.0
PPVCORE_S0_CPU_REG - 1.0 1.09
PPVCCSA_S0_REG - 7.9 0.79
PPCPUVCCIO_S0_REG - 10.3 1.03
PP1V8_S0_REG - 143 1.79
CPUIMVP_PGOOD - 603 3.28
CPUIMVP_AXG_PGOOD - 625 0.00

PP3V3_S0GPU_FET - 447 3.27
GPUVCORE_PGOOD - 520 3.27
GPUFB_PGOOD - 524 3.08
P1V05_S0GPU_PGOOD - 501 3.12

SM_DRAMRST# == MEM_RESET_L - 582 1.31


U5010
1 PPVIN_S5_SMCVREF - 290 3.34
2 GND - 000
3 PP3V42_G3H_SMC_SPVSR - 341 3.34
4 SMC_MANUAL_RST_L - 693 2.68
5 SMC_RESET_L - 493 3.23
6 SMC_TPAD_RST_L - 448 3.29
7 SMC_ONOFF_L - 686 3.35
8 PP3V3_S5_AVREF_SMC - 608 3.23


U2600
1 PPVRTC_G3H - 414 3.27
2 PP3V3_S5 - 106 3.28
3 SYSCLK_CLK25M_X2_R - 421 1.23
4 SYSCLK_CLK25M_X1 - 418 1.33
5 PP3V3_S0 - 283 3.28
6 SYSCLK_25M_B_GND - 0.00
7 GND - 000 0.00
8 TP_SYSCLK_CLK25M_ENET - 421 0.00
9 SYSCLK_CLK25M_SB - 411 0.76
10 GND - 000 0.00
11 PP1V8_S0 - 153 1.77
12 SYSCLK_CLK32K_RTC - 435 0.45
13 PP3V42_G3H - 286 3.35
14 PP3V3_TBTLC 395 3.27
15 SYSCLK_CLK25M_TBT - 416 2.25
16 GND - 000 0.00
17 GND

Do you have any hints on what to check next?

I've observed that inside two screw holes (wifi card , near J3502, and the one near the fan closest to the gpu, between C8431 and C8404) there are some scratches, as if someone tried to put the wrong longer screws inside and pressed them too much.
Please, do you know if under that two screw holes run some tracks?

I have unsoldered the two suspected bolts and watched the board in the area inside them with a microscope, scratched the layer but I haven't found any track inside, only the GND plane inside the one under the wifi board .
None of the respected masters here can point me to any direction, standing the above measurements?

Mobotool hat geschrieben:Please, do you know if under that two screw holes run some tracks?

Unfortunately - YES. There are tracks going through the centre of bolts on 3rd and 5th layer (signal layers). However, you should start with a well known issues - GPU and CPU SMPS controllers.

Hi Vogelek23, thank you so much for you suggestions!
I have already unsoldered from the board both two SMPS of GPU (U8900 ISL62882HRTZ) and CPU (U7400 MAX15119GTM) and resoldered them with SnPb tin, and I have measured :

CPUIMVP_PGOOD - 603 3.28
CPUIMVP_AXG_PGOOD - 625 0.00
PP3V3_S0GPU_FET - 447 3.27
GPUVCORE_PGOOD - 520 3.27
GPUFB_PGOOD - 524 3.08
P1V05_S0GPU_PGOOD - 501 3.12

From these measures I think that they are operating good, unless there is something wrong inside them and they can't control voltages through VIDs as they should...
Do you think that I should change them with new ones?
Please, can you write which signals go through 3rd and 5th layers under that bolts?
If I know that signals, I can verify if they are shorted to GND on other test points or components on the surface of the board, I would happily pay you if I solve this problem through your suggestions

Hi to all, sadly I still haven't found a solution to this problem, but I really want to

Please, Vogelek23 or any other with this info, can you point which signals go under that bolts in 3rd and 5th layers?
Are there signals under both the bolts of the wifi and the one near the GPU, or only one of two?

Thanks to anyone who gives me some suggestion