Does your old screen still work at all? If so you could plug in the old screen and see if it still works, if it does then your screen is probably bad. Make sure you have the plug snapped all the way in also, I have seen some only snap down on one side (just enough to power the lcd).
Some people have also claimed to have success by letting the battery run dead and then recharging it. I have never had to use this method so I am not sure if it works or not.
One last thing to try is resetting it again, sometimes you may not have hit the buttons just right and the reset did not take place. I just replaced a screen yesterday that I had to try 4 times to get it to reset (I accidentally hit the power button while the lcd was unplugged and got the white screen).
Hope this helps you a little bit, good luck.