Dell e156fpb ( I need help)

i received a dell monitor from a friend because he is moving and it was broken. i have spent endless time looking for the problem. when i turn it on it works for 2-4 seconds then the screen goes dark i can slightly see the mouse and desktop but the light for the screen turns off everytiem i reset the power. i was told to replace the inverter board because the power still works (light is green when turned on after screen goes dark power colour goes orange) i bought a new inverter board thinking this is the solution. so i excitedly pulled apart the monitor and installed the board. after it was installed and the monitor all back together i tried with a smile on my face only to find that that was not the problem. i have looked around and think it may be the backlight (lamps) for the lcd i am not a professional at monitors so i ended up here let me know what you think or if you need more info thanks guys