Hardware 3ds bottom screen question

[axxon]

okay i have a 3ds and the bottom screen was cracked, i replace the screen , it works fine but now the top screen doesn't work anymore. i notice that the top screen has power but doesn't display anymore can some assist me ?

 

[Quincy]

Check all topscreen connectors, perhaps the ribbon cable isn't inserted (correctly)!

 

[SmileCitrus]

If when you say the upper screen has power, you mean that the backlight of the upper screen and the green 3D LED are lit, then you can conclude the speaker cable is good, so you can rule that out. If those are both lit but you have no image on the upper screen, the problem is the ribbon cable for the upper LCD itself, so you should check that it's inserted properly and not dirty or damaged.