Mmmm had a simalar problem about 2 times and most recently on my 3 door , all times its been at my alternator , theres a blue wire goes ont a thread , shouldbe the same colour i think on yours , anyway i think this sends a signal to the battery to charge it ? i might be wrong , but 99% sure , anyway had this type of problem recently and checked it out the other week and mines was all split and corroded , got new connector , redone the connection and shes been great since , bought a new battery too before finding this

Maybe even worth cleaning it up just incase , even if it looks ok