No power after screen replacement.

I have a 4th generation iPod touch. The screen was broken, so I decided to replace it. The iPod was working with the broken screen before. After installing the new screen it does not power on. I tried to reset it by holding the power and home button, nothing happened. I followed the instructions I found here, to ground the battery. Touched the right hand side battery terminal at the same time time with the metal piece by the home button, but still no power. Any idea what else can I do? Thank you.