How can I tell if my phone will work after screen replacement?

Hello! I have an engineer friend that can replace screens in a jiffy, he just asked me if my phone works fine, because if not the replacement will be worthless. I cracked my screen a few days ago and the phone was working fine and even the display, but now the screen is discolored. I can't unlock it, but I still can kinda see notifications. Yesterday I made a call, but I couldn't hear it ringing (nobody picked up). SO what do you think?? Should i get the screen repaired? Does it sound like it's going to work?