A method for assembling an electronic device comprises inserting a thermal element into an electrical connector contained within a special volume defined by a constricted enclosure that comprises a housing of the electronic device. The spatial volume contains a printed circuit board and the electrical connector includes internal electrical contacts that are positioned proximate to solder connection pads on the printed circuit board when the electrical connector and the printed circuit board are contained within the constricted enclosure. Insertion of the thermal element heats the internal electrical contacts so that solder on the solder connection pads reflows to form solder connections respectively between the internal electrical contacts and the solder connection pads. Thereafter, the thermal element is removed from the electrical contact.