My screen was cracked, and I replaced it. Now, the screen stays lit for about 30 seconds on start up then the backlight shuts off. I can see the screen output with a flashlight, so it is still working wtihout the backlight. Also, once it shuts off, If I close the screen and open it again it will illuminate for about 5 seconds then shut off. It does this everytime I open and close the laptop. The cracked screen always stayed illuminated, so I am wondering if this replacement is defective. The only thing different with this screen that I can tell is that the cable going into the inverter uses an extension to make it reach. My original screen did not have an extension to the inverter. I wonder if this is causing it? It is long, so I had to stuff it in the cracks to get the bezel on. Not sure if this would cause this symptom.
With my experience, open the screen again and connect all the cables on inverter and screen very carefully. If these cables are properly connected, please check the fitting of inverter if its been there fitted properly, or open it and pack it nicely and carefully again. I think this will resolve the problem. If it doesn't resolve the problem you can test screen back lights or try another screen on your laptop.