Be mindful of the battery data cable and make sure it doesn't get pinched or trapped under the battery board.
If your battery came with adhesive pre-installed on the bottom, flip it over and carefully peel away the liner to expose the adhesive. If your battery did not come with adhesive, apply a thin double-sided adhesive tape such as Tesa 61395 to keep your battery in place.
Carefully position the battery and set it into place.
Press and hold each cell firmly for 5-10 seconds to secure it to the lower case.