Use a quarter not a nickel. The battery cover is purposely tight to create the proper connection to produce the moving flame effect. Place quarter in the groove. Press down very firmly and turn cover slightly to the left. The battery compartment cover will spring open. The battery loads + side up. Line up the two cover tabs to match the housing notches and hold cover firmly in position. Place the quarter into the grove and press down firmly as you turn the cover clockwise to close. Be careful to avoid touching the wick as you load the new battery into the tealight. Each tealight uses one lithium CR2450 battery. We offer replacement batteries for your tea lights.