After battery replacement touchscreen wont work!

Hello guys!

I've just done a battery replacement for the galaxy s6. It went smoothly.. placed a new battery inside and closed it right up as new. When i booted my phone... the touchscreen does not work!?!? power button and the home button work because when i place my thumb on it, it responds.. but the screen is not working whenever im swiping with my finger...

Can someone please explain why? did i damage something when i was replacing the battery or did a cable unplug while i was putting the phone back together?

Thank you