Why is the screen white after a new LCD replacement?

Hello,

So I bought an iPhone from this guy, a really bad choice because the phone was old. But after a few months it started having lines (blue and white) up and down the screen. The phone can still operate if you remember where everything is, but obviously you can't see the screen. So someone told me to replace the LCD, which i did. I did everything without any issues, following a video tutorial. After installing I turned the phone on and it showed the apple, then it went to the white screen. I tried reseting it and what not still the same issue. Also, when you plug it in to the charger you can see the screen, once you slide the unlock button it goes back to white and the only way to get rid of it is to put it to sleep and then turn it back on again.

I would really appreciate any feedback on this!

Thanks!