Replaced Glass now Screen Not Working

I am sure this has been asked a million times already, but I just replaced a screen on a Galaxy S3, no problem getting the broken one off and putting the replacement in place. But when the phone is powered back on the screen is not responsive. I was thinking maybe I didn't connect the buttons properly so I removed the glass again but they were attached correctly and all looked well. I then placed the battery back in before replacing the glass again to check and even directly on the LCD there was no response.

I did not check the phone prior to replacing the glass so I can not say for sure that it did work (not my phone). I am stumped, does the LCD need to be replaced? What would cause this issue.

Thanks in advance for any quick responses, I really need to get this done and back to them quickly.