HP DV9000 black but glowing screen and works on external monitor

Hello,

I'm having a really hard time with my old HP DV9000 since the screen just stopped showing anything. Once I turn it on the screen starts glowing, but I get absolutely no image. I tried connecting my VGA monitor and it shows everything except that there are blue vertical lines all across the screen. I already tried hundreds of posts telling to take out the battery, ram and so on. An hour ago I tried a trick with letting it heat up by putting towels and other stuff on it and it magically turned on, but the problems was that there were the blue dotted lines again and it didn't even boot up. After that even if I heat it up it doesn't start again. Any solutions of what might be happening please?
Thanks!