Nirmith Akash Anawarathne :
Problem can be in your built in display or the motherboard most of the time. But i think it's good to leave it to a expert because those cables and the dissembling the parts in the screen are bit sensible. Other wise there's no way to check that if it reach BIOS and have a screen problem or a total motherboard failure. Mainly because you can't use HDMI or VGA to see Laptop BIOS. So try a temporary display replacement and continue with the rest if you capable of getting a display.
but i think if the problem coming from the display screen, the laptop should runs normally but the fan start work hard when i turn it on so i think the problem in integrated graphic card and it's irreplaceable, right ?
For those 3rd and 2nd Intel laptops there's little possibility of upgrading the CPU. Mainly because it came as a PGA Package and most of the time not soldered to the motherboard. If there's dedicated GPU so you can't think of replacing it but for the CPU sometimes it work for exact same models.
But so far i didn't see any 2nd 3rd model of your laptop everything is about 1st gen (BGA1288). which clearly means soldered
so there should be only one move to make... changing the board but i think it's pointless. Laptops boards are quite high in price even the old ones so best thing is to save it for new one. which is what i would do.