Lenovo yoga 3 14" - The laptop switches off after few seconds

Hi,

I have a Lenovo yoga 3 With the motherboard BTUU1 NM-A381.

When I switch in the laptop, only the led switches on for a couple of seconds and then it switches off. (The fan and the keyboard light do not switch on). This happens either under ac or under battery. However the battery charges correctly when the ac is connected.

I tried to remove the battery hold the power button for 60 seconds but it did not work . I also removed the ssd, the fan, the LCD , the ram from the motherboard but nothing.

I checked the voltage on the motherboard after the led switches off and it is still powered even though no life signs are visible. For really shutting down the computer I need to hold the power button for 30 seconds. I also detected a component called 6414A which becomes very hot (if you touch it you can burn your finger).

What is the rule of this component? Could be the reson behind the issue?

I also noticed there are other chips on the motherboard which have the same name but do not warm up so much!

I attached a picture of the motherboard and the components. The yellow signs are on that one that warms up, while the green signs are on the other component with the same name that does not warm up.

Many thanks,
Carlo

Check resistance between D-S and S-D from warming transistor and resistance to the ground from that pins. Check too resistance from B+ to ground and write here all.

Thanks for the answer.

Warming component (yellow signs in the picture)
S-D. Open

D-S. open

B+ ground O.48 M ohm

Good component (green signs in the picture)

S-D 0.74 M ohm

D-s -0.72 M ohm

B+ ground 0.72 M ohm

Change warming transistor. Write resistance to the ground when motherboard is off from all coils. How looks power consumtion and voltages from all coils when motherboard is on?