Help with Lenovo P52 - no charge, no power on

[nemitom]

Hello,
I have problem with Lenovo P52. (I7 - 8850H)
On battery is not problem - work normal
On external power supply - after connect only one-shot blink white LED and no start...
Power supply is ok, battey is ok

Where to start measuring? Is this a common error?

Thanks All.

[mcplslg123]

Voltage on Source/Drain/Gate of dc-in mosfets? Only power adapter connected.