Ram gen 2 cummins no buS - wont start

[Chris Allred]

I drove my truck on Thursday and pull my RV over in Pacifica on the side of the road. Today I went to leave and it won't start. The odometer is saying no buS. I used starting fluid it would run briefly. I could smell something electrical and when I looked at the fuse panel the exterior was melted. Also what appeared to be a ceramic plate inside the fuse panel was burnt. see attached picture

I would really appreciate any suggestions or helpful comments on what is wrong.