Figure out what caused this issue. I would replace it all, including the breaker. The breaker should have kicked.
Breakers aren't supposed to kick for series arc faults unless they are arc fault breakers. An arc fault is amply capable of doing this.
Just curious as to what would have melted a wire nut.
A limp wristed wire nut job, of which the usual sign is someone taping the nut and wires, because their experience is if they don't, the wires fall out of the nut! They figure if they tape them they won't fall apart. What they're overlooking is the connection inside the nut is loose and won't do its job.
Or something get under the nut that was not supposed to be there. I always tape the wire nuts for this type of thing. Keeps dust and debris out of them
Present company expected, of course
Well, I have my doubts that a properly torqued wire nut will *allow* anything to worm its way between the two wires. Those wires are pushed together tight, forced into a very tight spiral, and dug into a bit by the metal wire-nut "threads". They aren't just "held against each other".