Have you tried pushing the reset button on the back under the antenna?
Try turning it on and listen for any sound, like the start up beep. Do you hear any sound at all after 30 seconds?
There's a couple possibilities that could have happened.
1. The screen and/or main board has been damaged.
2. The screen cable has come loose from the main board.
If the unit is under warranty (registered with Garmin) you can call them and see if they will fix it for you. They may charge you if they determine it was dropped or mishandled.
www.garmin.com
If you have problems with getting them to fix it for you, I'll be happy to look at it for you and give you a quote. I have repaired many Nuvi's and I have references.
If interested, please email me at ks3r at sharc dot net.
- Jim