Nexus 4 melted itself when connecting charger topic

Went to put my phone on charge this morning, the nexus 4 started to over heat really bad and smoke was coming from the charger port when the charger was plugged in, in mere seconds the charger port was melted and crusted and the charger lead itself also done the same, tested with a few leads and it's the nexus device whenever the lead connects, the phone is perfect working order, never dropped or water damaged, this was purchased roughly a year ago and nothing has ever happened like this until today.