Replacing Outdoor FloodLight
This is EXACTLY WHY connections should be in a fixture or junction box!  You may have had a short directly in contact with wood.   If it were my house, I'd carefully open up that and after determining where exactly the wire goes (so as not to damage it further), cut an opening for a fixture box.  A rotozip would be a good tool to use.  Be sure the power is off to the circuit.  You might be able to fit an "old work" box like this. This would also expose a bit more of the cable to inspect for damage.  The wire might be a bit short to meet code, but that's something you could probably live with. 
If you're not comfortable doing this, yes, call a pro. 
  Old work box