Why doesn't my screen display anything?

I was using my iphone and then suddenly the screen went black, but the phone was still on (it vibrates). I tried resetting it and I took it to apple, but they want me to pay 300 to replace it. Then I asked a friend who repairs phones and he said that a certain chip is damaged that isn't allowing the screen to display anything. It would cost me 140 for him to replace the chip. I tried opening the phone up myself to see if everything is connected properly and it still doesn't work.

I'm not so familiar with the parts of an iphone but i'll try my best to explain what I think. I think that my friend who told me I have to replace the chip is wrong. I feel like I can just replace the screen and it will work, because the digitizer still works. I can swipe the screen and turn it off, but I can't see anything. I have to guess where the "slide to power off" option is, but it still works when I swipe the screen. Do you think it's worth trying to buy a new LCD and replacing it myself? Or should I just give it to my friend and pay the 140?