LENOVO IDEAPAD 3 14ITL05 dead

[smic717394]

Hi, I have a LENOVO IDEAPAD 3 14ITL0, apparently was working one day, dead the next. It has orange light so it does charge the battery (see photo 3) about 1A. Without the battery its 70mAh. Non of the coils have low resistance. The 3.3v is present, the 5v is present, 1.8v is present. power button has 3.3v, the bios chips have 3.3v. I tried removing the rtc to reset the bios, with no change. I tried to reflash the 2 bios chips, with no change. I tried unplugging everything from the board, no change no matter what 70mAh like in the photo.

Checking with the thermal camera, as soon as the adapter is connected looks like the 70mAh goes to the PCH, it gets warm like in the photo. The bq also gets a bit of heat but all voltages around are good. Since I get orange light and its charging I assume the KBC is fine. My guess is the pch is bad, I will try to check for shorts on the 3.3vLDO and alw_pch and 1.8v alw_pch, but I´m stuck. Need a bit of directions.

One thing I noticed, with the battery removed, and adapter, if i press the power button and while pressing i connect the adapter, the white light on the side comes on, the power button flashes 2 times, the it dies. Even when the light on the button came on for 2 seconds it was always 70mah and just the pch have heat.

[mcplslg123]

What about 1V? Is it present?
Mb markings?

[smic717394]

This is the board. Ill check for the 1v

[smic717394]

I checked the 1,05V on UX4713 (cpu) and UX4604(pch). The input 1.05V 1,05v on pin 1 and 3v on pin 5 its present on the 2. but no output in pin 4. I tried injecting 0,8V on pin 4 and on the cpu one the voltage drops and the same corner lights up, so I think is game over for this. Bellow its a video of the fault.

https://drive.google.com/file/d/13-L...usp=drive_link
https://drive.google.com/file/d/1Spm...ew?usp=sharing

[mcplslg123]

If the cpu/pch receives a voltage rail, wont it heat up a bit? Not the way to diagnose a fault.

[smic717394]

Of course if it gets powet it heat up. But its not normal fot the voltage to drop. Inject 0.8 on pch, tje voltage stay 0.7 and the current is los 70mah, you ingect 0.8 on the cpu where should be 1.05v, and the voltage drops from 0.8v to 0.5v and the current is 250mah and the only bit thatvgets hot is the same corner that flare when connecting the adapter. So voltagevdrop on cou, allot of current, same corners !nd all other voltages are present, fot me its obvious the cpu is dead. If you have any idea please share it instead of poing the obvious.