iPhone 6 wont turn on after screen replacement AT ALL

So I recently changed my iPhone 6 screen (last one was cracked and had broken LCDs). I bought what I think to be a good screen for 40$ and I carefully put it all together. After I was done I put it on the charger to charge because I haven't used it for 2 months after It was broke. I left it charging for 4 hours and went to turn it on and nothing...

Here is everything I've tried

-Tried connecting to ITunes.. Did not work

- Disconnected the battery and plugged it in to the wall and got no Boot Loop or anything

- I've only plugged in the LCD's and haven't completely put in the screen to the device so no screws hit the wires

- I hit the Home button and the power button and held it for 30 seconds

So what do I do?

If it was the Battery's problem wouldn't it still boot up when I unplugged it and plugged in the cord.. And if it was the LCD's problem would the Phone connect to ITunes? I'm so confused... Some people tell me I need to charge it for 24 hours before it can work?