Won't come on, tried taking out battery and that

The problem could be with your screen. It looks like the led light of your screen is dead you could follow up this solution.

I have had this same problem with a HP DV2000 and the problem is not the contrast light. What it is, is that the laptop thinks that the screen is been shut down that is why the light does not come on. The best way to solve this is to remove your keyboard first.

You can remove the keyboard by removing exactly 7 screws from your laptop back, there are 5 screws located under your battery and other two that are in the location of your RAM'S.

Just open them up and then you will notice that the key board pops out abit then just simply take it up and then just below the keyboard, on the same line where HP brand logo is on your machine there are two small clip types of pind, that you can remove and put back.
There is a clip that is hidden abit under the metal plate, so just try and remove that clip from its place using a needle or any long and thin object.

That will make the laptop not have the problem. But once you remove that the laptop constantly will think that the screen is open even if you close it. then after like a week or two you can put it back and all shall be fine if not then just remove it and keep it out.

You can then set your power options to shut down the screen light every 2 minutes or something like that so as to avoid the backlight being switched on all the time.

Hope this solves your problem.

I think the problem is with your LCD screen.

Try connecting it to external monitor and see whether a display will come up on the external monitor. If this the case, update your video driver. If you had updated video driver but still no display I suspected your LCD screen is faulty and needs to be replace.

(if machine is under warrantly, no need to pay any fee for replacement).