ThinkPad T470s dead

[rumpumpel1]

Hello guys, I have a ThinkPad T470s that no longer starts (black display). As a reference, I have another T470s board that works normally. The defective board (with fan and display only) shows power consumption as shown in the linked image . The lower chart shows the defective board (it stays at 500mA forever), the upper chart shows the reference board. x-axis shows seconds. The heat sink also gets warm. From all this, I conclude that the CPU is operating.
The fuses are all fine and a visual inspection of the board showed nothing unusual.
I also checked all the voltage rails and various signals such as RSMRST (1.0V), SLP_S3, SLP_S4 and SLP_S5 (all 3.3V), as well as RTCRST (3.0V) and PWRBTN (3.3V).
They are all identical to the reference board.
Next, I flashed the BIOS with a clean ME region and I also flashed the BIOS from the reference board, but that didn't change anything.

What could I check next?

[kalilinux25]

Re: ThinkPad T470s dead

Hello guys, I have a ThinkPad T470s that no longer starts (black display). As a reference, I have another T470s board that works normally. The defective board (with fan and display only) shows power consumption as shown in the linked image . The lower chart shows the defective board (it stays at 500mA forever), the upper chart shows the reference board. x-axis shows seconds. The heat sink also gets warm. From all this, I conclude that the CPU is operating.
The fuses are all fine and a visual inspection of the board showed nothing unusual.
I also checked all the voltage rails and various signals such as RSMRST (1.0V), SLP_S3, SLP_S4 and SLP_S5 (all 3.3V), as well as RTCRST (3.0V) and PWRBTN (3.3V).
They are all identical to the reference board.
Next, I flashed the BIOS with a clean ME region and I also flashed the BIOS from the reference board, but that didn't change anything.

What could I check next?

Hi it will be always easy to assist you if you put the complete model and part number fof your model, after that look for the schematic and post it in here for easy references

[rumpumpel1]

Re: ThinkPad T470s dead

here is the schematic

[kalilinux25]

Re: ThinkPad T470s dead

here is the schematic

PQ1 AND PQ2 has 19v?

check if 3v and 5v present ,

if you dont have any voltages in PQ1 and PQ2 maybe you have a shorted mosfet

PQ1
resistance to ground
PQ2 also

[rumpumpel1]

Re: ThinkPad T470s dead

PQ1 AND PQ2 have 19V.
3V and 5V rails are ok.

I'm wonderng about your questions: as I described in my initial post, the CPU is running, the heat sink is getting warm and the current consumption also indicates a running CPU. How can that be without having 19V at PQ1 and PQ2 and without having working 3V and 5V rails?

[mcplslg123]

Re: ThinkPad T470s dead

Abolutely right@rumpumpel1. What about DRAMRST# on bad board?

[rumpumpel1]

Re: ThinkPad T470s dead

for both boards DRAMRST = 1,2V