battery won't work now?

Well I took my iPhone apartment screen was broke. While I took it all apart I was putting the battery back and connecting the lcd to make sure it worked. Now I tried it again cause I took it a part again. And now the lcd won't turn on and it does not make that beeping noise when plugging it into charge. Also when. I try to connect the battery the left side of the connection right by where u put the screww, it won't snap in. Is this problem on the battery connection or the motherboard connection?