Laptop Screen flickers green and pink

Hi. I own a Dell Inspiron 15 3000 series laptop. It's out of warranty. Now the screen is flickering green and pink, even when I turn on the laptop (with the dell logo and everything). When I connect it to an external monitor (in this case, my TV via HDMI), there's nothing wrong with the images shown on the TV but my laptop screen still flickers green and pink. I've also tried removing the battery and putting it back in but to no avail. My graphics driver are up to date. Please advise on what the problem could be. If it's an lcd problem, how much does it usually cost to replace? THanks!