If the monitor lead has been shifted to the new card's socket then and firmly pushed home it should work. Even without drivers you would normally expect to get something on the screen.
You could try inserting the card in and out a few times - sometimes you can get oxide on the edge connectors.
Yours is a completely different problem. You should therefore raise a new post of your own so that you get focussed attention. There are many possibilities but power supply unit failure is fairly high on the list.
We all live on a ball.