My laptop doesn't turn on, black screen, fan runs

Hey,
So my laptop is hp pavilion g7, it's been working for 6 years
Today I took it apart to clean it, and put all together, and it's not working anymore!
This is not the first time I clean it, I don't know what happened this time

When I boot it, the fan runs at maximum speed for as long as I keep it, the screen does not turn on at all
I tried taking off the ram, the behavior was the same!!!

Check this video, nothing attached to the mother board, no ram, no hard drive, no cables, no links. Only the battery and power button, it runs like that, and it's absolutely no differece when I put every connection and every part in the mother board again
https://youtu.be/ZEAvjyb-BLU

Please tell me what is that and what should I do.