Chosen Solution
I replaced the cellular antenna in my iphone 4, before i dissembled the device everything worked completely fine, after reassembly the screen wont light up, i can hear sounds but there is no picture.
Reset, hold both home and power buttons for about 10 seconds until the iPhone begins to restart. If still nothing. Check that the front screen connectors are perfectly pressed down into place on the logic board, especially the LCD Display connector.
