Kindle Fire HD screen issue

I'm having an issue with a black screen on my Kindle fire HD. I have tried to reset it numerous times, its charged up, it makes the volume up & down sound, and the power off sound. I can see it get lighter when I turn it on & there is one line thru the screen but I just can't get the clear full color back. I've disconnected the battery & plugged it back in and that worked once for me…. I tried putting it in the oven minus the battery as I had read somewhere…. still nothing. I must say that I didn't realize how much I depended on my kindle till it kicked the bucket. Is there any hope for it or is it a firmware issue? Will changing the motherboard help with this issue? Thanks!