OKAY people, dumping the Mobo for this, IMO, little thing, is probably unnecessary waste, unless you are itching for a new Mobo anyway.
Do you understand what this connector does? Is a simple 12V feed, that's it. It only provides 12V to the Mobo and that's all it does. 4 of those wires are ground and the other 4 are the 12V. Missing just one wire is not going to affect in a major way, I would just go without that one wire by cutting it off completely. BUT, if you want it perfect, a new Mobo$.
The connector pin is burnt and some plastic melted. The heat could have also damaged the traces under the pin, and that damage is unknown if it goes further. Continuing to use this port could cause further damage that might not be limited to just these pins. It could cook VRMs, damage the socket or CPU, or even short out at the connector and start a fire. I'm not about to tell someone to McGuyver a connector and risk them getting further damage to their equipment, or possible injury to themselves.