Question Power LED goes on but quickly goes off, with a "tumble" sound, and this goes on in cycles, while nothing else happens

[andrefrsilva]

Toshiba Satellite L850-1V7
Power LED goes on but quickly goes off, with a "tumble" sound, and this goes on in cycles, while nothing else happens.
A video of it: https://drive.google.com/file/d/13dR7WQ_6y-RySQCyqYUWP1oioxTrJcU5/view?usp=sharing

I bought a new motherboard and a new CPU and everything is still the same.
I tried a different power source, but the same happens. The laptop requires 19V. The power sources measure ~20V and 21V.
I tried to disconnect every connector and simply connect the power to the motherboard, and still, the same happens.

 

[Ralston18]

Video shows a PCB but thereafter the video does not (for me) play.

Just a black screen with the "endless" circle.

 

[andrefrsilva]

Maybe here: https://1drv.ms/v/s!ArkSHQ8jeIoc9SpQ4zh55Yq7aXx_?e=T1TlxO
It's just the LED going on and off. And there is a sound in parallel, like a "power up" rising frequency, which quickly falls as the LED goes off. And on and on.