Changed top screen, now won't power on

Changed the top screen with no issues, now it won't switch on. The green 3d Light flashes quickly and neither screen flashes. I have taken it apart again and double checked all the connections and everything seems to to be in as far as it should etc. I thought maybe as the 3d light by the 3d screen was flashing that it might be those 2 tiny connections, but they seem to be in fine. Any help would be greatly appreciated.