Next step: fix it. Replace the cable from the service panel to a little bit beyond the failure point, and join up the new cable with the old in an accessible junction box. Can't tell how extensive the fix would be without knowing the layout, but the big effort is likely routing the new cable through the ceiling, walls, etc. If it's an easy run to the panel, it's an easy job.
You could probably get away with replacing a small segment of cable around the failure point (2 boxes), but I'm leery of heat-damaged cable. Cut out a big enough chunk to be sure the remaining cable is undamaged.
Now wait for a real electrician to comment.