Black screen after LCD replacement

My iPhone 3GS had a white screen with vertical stripes, so I have replaced the display. The power switch was broken, so I could not turn it off before changing it. I have also changed the rear case and the power switch. The repair went well, but now the display is completely black, with not backlight. The iPhone vibrates when the mute button is turned on and off, and it is recognized by iTunes. I checked that the connector #1 was correctly plugged. I've also tried to restore the iPhone but the screen is still black. Can this be fixed?