LG G2 phone- phone goes black and is unresponsive to anything when answering a call

[AC Question]

I had my phone screen replaced a couple days ago, and have only just tried to make a call, it goes black as soon as I press the call icon and then becomes unresponsive, it does the same thing if i try to answer a call. The light on the power button at the back is still on...but I'm wondering if maybe something wasn't done right when the screen was replaced?
Is there any way I can fix it myself? If anyone has had a similar problem...