A method of assembling an electronic subassembly for a personal care product by providing an adapter having a body with a tapered guide surface. A first circuit board is positioned within the adapter. A flexible portion of the first circuit board extends from one end of the adapter and a rigid end of the first circuit board extends from the other end of the adapter. A housing is provided with a first opening and a second opening and a chamber (between the first and second openings. A second circuit board having an electrical connector into the chamber thru the first opening. The tapered surface of the adapter engages a corresponding tapered guide surface of the housing. The rigid end of the first circuit board is connected to the electrical connector.