Chosen Solution
so my son opened his iphone 8 up with intention of replacing screen could not do this because his screen did not come with the LCD part to the screen so we put it back together all seems to be working except the screen is black. any helpful advice please
Did your son disconnect the screen assembly from the logic board? If he did, did he disconnect the battery first? Not disconnecting the battery can cause the backlight circuit to fail. To see if this is the issue, connect the phone to a charger or iTunes enabled computer. Then shine a bright light on the screen. If you can see a dim image, then the backlight circuit is damaged. This would require a micro-soldering repair. Hopefully, your problem is just at the connector level as Troy suggests.
Take it apart again and make sure all cables are in tact (not ripped or broken) and plugged in. Hopefully a cable just came loose while you were putting it back together. What was the issue that caused you to open it? If the screen was failing perhaps it failed the rest of the way?
His screen was broken and he went to replace it but after he opened it and got it all apart he realize the LCD wasn’t in the screen so he just put it back together and it was black it is working al nice and vibration just all black
