try to check the track at this tp fourth with a multimeter. This track is devoted to checking function usb ic function, in other words u2 in iphone 5. if among the four or all tp contains a small or large ground, means ic u2 short circuit or damaged and immediately replace it. if examined does not contain ground, instead of u2. the size of the short circuit must be true if damage to u2. if there is no short circuit on the fourth tp, please check the battery connector. usually at the time of replacement batteries for the revocation of the battery connector flex too hard and less conscientious, could make battery connector on the pcb become shaky, as a result the battery is not detected by the gas gauge and the circuit is directly protected by way of breaking the current to the battery lines. iphone will reboot loop. if this is the case, then immediately re-solder on swi bat and bat pin ntc. Safety plug the battery into the meeting, in order to avoid a gap between the spark plug.
I am happy to join here, to share knowledge and experience sharing.
you are all professional technicians?
solve problems and continue to learn ,,, good night ...