Black screen and vibrates every 3 secs

Hello friends:

I have an iPhone 4g that it fell by the side of the screen, but not broken. After that, screen is black (there is no image), and vibrates every 3 seconds if charger is plugged. If charger is not plugged it not vibrates.

iTunes recognizes it, and I have restore software, but don't work.

I have put a new screen (LCD + touch), but issue still. This new LCD screen work perfectly (I have tested in other iPhone). Connectors are well (I have seen under microscope), and I don't know that I can check.

Please, I need help!!.

Thanks!!.