3DS xl Blue light and Green light no screen/not booting but backlight

So I took apart a 3ds xl to clean it because it smelled like cigarettes, I managed to clean and when I put it back together it didn't work I tried to go into safe mode and the blue light and green light turn on but the screen wont and the backlight turned on. So I took it apart again reconnected all the ribbon cables again and I turned it on without screwing anything and I just hold the battery in place, it turned on so I screw it back together and it didn't work again, so I dissembled it again did all the same things I did the first time and tried turning it on without screwing anything in and just hold the battery in place but it didn't turn on just blue light and only the backlight of the screens were on. What do I do? And what could be causing this?