My friend recently purchased a vintage Fender Bassman without a cab (yet), and found that some hardware in his guitar was loose, so naturally he decided to test out his guitar. He tried to test the sound through a very low voltage-capacity speaker in my amplifier, which was not a good idea at all. Shortly after, his amp made a loud clicking sound, the light indicating power was off, the tubes no longer showed any signs of illumination, and a slight smell of smoke was present in the air.

We are curious as to maybe what happened. Obviously it is serious, and YES we know that we are idiots no need to point out the obvious. In addition, if anyone knows what could have been damaged here (perhaps the tubes?) that would be extremely helpful. Also, if someone could give us an idea of what type of professional we should talk to about this, it would be much appreciated.
I Want One!!!

The Kraftwerkers: The Society for the Appreciation of Kraftwerk
Well it could be a number of things. Start researching amp repair places locally.