1. Leave it on the charger for a bit (perhaps the battery is drained?)

2. If that doesn't help, perhaps try to pull the battery and hold down the power button for about 30 seconds, then reconnect and try to reboot.

3. Perhaps your screen is bad? Does plugging the old one back up yield the same results?

4. If none of these help, check all of your connections make sure your ribbon cables aren't torn and are completely plugged in.

5. Let me know what you find.