I am trying to remove the screens, but can’t seem to get them off. I have already removed the screws from the screens, but...

If there is no feedback from the power button, then the outer shell has probably been knocked out of place. The button is attached to the shell and is supposed to be over the power switch, but the button can fall out of place. You can follow the steps in the Reemplazo de la carcasa exterior to set the outer shell in the correct place again.