At this point if it was me I would first check to see if the displays flex cables may have popped loose. Unfortunately they reside right below the display. Instead of lifting the display right away I would try removing the back housing from the phone to gain access to the motherboard. You will not be able to see the displays flex cable connection to the motherboard as they are on the other side of the motherboard. But if you look at the guides on this site you can get an idea of where they are located. Once you have an idea of where the display cables connect to the motherboard you may try applying pressure to that area of the motherboard to see if maybe you can hear the display connection snap back into place. If it is loose you may hear it snap into place or you may not. After you have applied pressure to that area go ahead and try putting the battery in and try powering it on to see if you have a working display. You may attempt this a few times. If that doesn't work try to very carefully lift the display to check the display cables. If they are tightly connected to the motherboard then you know the LCD or backlight in the display is damaged and you will need to replace the display. Hope this helps you out.
Here are the guides for this device:
Samsung Galaxy Note 4 Repair