HP Pavilion zt1150 laptop display not working

I have the HP Pavilion zt1150 which is nearly 3 years old. For some time the laptop display would just flicker and if I hit the little display shutoff pin thing by the power button a couple of time the display would tend to come back on and run for while until I needed to do it again. Now the display just doesn't come on at all. I've have a tech take a look to see if it was the inverter cable and that wasn't it. He seems to think it's the mother board. Though I'm wondering if it could be that the battery is completely dead and that may have something to do with powering the laptop display. For now I have it hooked up to a monitor to see my desktop. Has anyone else experienced this or heard of possibly a dead battery also killing the display? The odd thing is that I can just faintly see the desktop on the laptop screen, though not nearly enough to conduct any work.