After reassembling my laptop it just black screens

Hello, I recently reasembled my asus k55n. I put it together, making sure everything was connected. The first time I did not put just hard drive in but I kept my 2 sticks of 4gb ram inside, it booted then said it was missing the hard drive (good it had a display) so I turned off my laptop and put my hard drive in, then things turned on me. My laptop would start, you could hear the disk check and the fan. The lights toward the bottom light up WiFi and a light bulb that I assume stands for screen? Anyhow, what it does is just stays at a solid black screen, tried an external monitor but all that happened was a black screen, my laptop has faintly flashed an illuminated screen so I saw a faint lighting I have swapped hard drives, ram and all I get is a black screen.. If need be I can post photos..