HP Pavilion DV9000: won't turn on after disassembly, what should I do?

Question

Do it yourself

Notebook HP Pavilion DV9000.
Won't turn on after disassembly.
When the AC adapter is connected, the LED at the socket on the laptop lights up.
Nothing happens when the power button is pressed.
I sin on the train. I tried to replace the power cable with a cable from the multimedia buttons, it does not work. Now I fixed the cable from the multimedia buttons (it is called by the tester), stuck it in place of the power cable - it does not work. The loops look the same, but they are connected the other way around (from multimedia to its socket with contacts up, from power to its socket with contacts down, connected the multimedia cable to the sockets of the power cable with contacts down).
How to proceed? Of the tools there is only a tester.
Disassembly video (construction visible):
https://youtu.be/D7e4s-gwy1Y

Answer 1

Weird question. Of course, you need to carry the laptop to the service center.
I also don't understand why it was taken apart.

Answer 2

Did you touch the button? MB does not receive a signal from it? Just check all the connectors - move them, stick them in better.
I don’t remember how on laptops, but on an ordinary mother you can check by directly shorting two legs on the mother - if it starts up, it’s crookedly assembled.

Answer 3

I had the same laptop, took it apart many times, without problems. He still knows how to turn on if you slide your finger over the multimedia buttons. It's like you're dusting them off. Try this, maybe something is wrong with the power button.

Answer 4

UPD: I closed the G2 contact on the board with tweezers, the laptop started up. How to determine if the problem is in the power button or cable?