Replaced Flex cable ad digitizer but still no signs of life from the LCD screen.

I have two Samsung impressions. One that had a problem with its digitizer, the other with its flex cable and discoloration on the screen. I decided to replace both the digitizer and flex cable in the first one (after the original stopped working) and replace the flex cable in the second one.

Here is the problem. The first phone is having problems turning on all together. None of the keyboard lights come on. I know for a fact that the screen and the flex cable worked in the first one. In the second phone, the key board lights up and it vibrates but the screen remains blank. It doesn't even try to come on. I have tried two flex cables and many different digitizers.

Has anyone had this problem or has any advice? Is something not pushed in all the way?  I really need this phone for school and my mom. I have put these phones together many many times. I'm stuck.

When I say discoloration I meant I could only see half of the screen and the colors were off. But I will try again and see if it is indeed the lcd screen or something that's not installed correctly.