Computer not turn on even plug in the power cable

As subject, computer canr turn on.

Things I think did:
At first my display is not active with como, then i go to remove it and put it back but still no react.
Then i remove those rams and try(remove and plug in back the display card as well)
At first, comp still running, then 2-3 times later, como totally no reaction...would like to know if i spoil some hardware already?
the lightbub on mother board not light up in the end...