Before Install it comes on. After it Installs it doesn't.

I have a White Galaxy S6 in my shop for repair. The new screen came in today and before installing i connected it to the motherboard and it worked. Now, after taking off the tape protector and put the LCD into place it stopped working. I took it off and it doesn't come on at all. The ribbon is connected properly but still no life in the LCD. What could cause this issue to come up?