How do I fix a burnt charging port?

I recently received a Samsung Galaxy S7 Prime from a friend. He told me that when he plugged it in to charge one time it caught fire on the charging port and he had to use a fire extinguisher to put it out.

I took off the back cover and it has no water damage from the fire extinguisher, but the charging port on the bottom of the phone is extremely burnt out of shape inside of the port and out. The phone is in almost perfect condition externally, so I would really like to fix it. There are no cracks or burns on the screen, and the battery is not swelling.

I have fixed tablets and phones before but I have no idea how to go about fixing this problem, and I don't even know how to open the phone to see the internal damage to the port. I have tried plugging a lightning cord into the phone to try and power it up, but the inside of the port is melted and the plug does not fit all the way in.

How do I open it up to see the damage to the port, and how do I fix the phone? How much will the fix cost? Will I have to replace the logic board, or is the charging port a separate part? Any answers or help is greatly appreciated.

Here is a picture of the port: