As far as any house(wood) construction goes I would argue that rebuilding should take place for all but the smallest of fires.
Problem with wood is, when it reaches a given temperature (before it starts to burn), it will start to lose strength in a process called pyrolysis, this strength can never be replaced the wood could be structurally unsound as a result.
It looks like in the first picture, there must have been a good seal between the drywall and the front of the panel body.
Just as a little question, is that tape below the left of the panel serving as some sort of a bushing?.
Or do the wires go behind that stud?.
