OK, so I examined a duplex outlet installed in a floor and discovered something interesting and dangerous. The outlet was not contained in an electrical box of any kind, but was installed in a hole dug into the wood. Also, the BX armored cable remained below the floor with the black and white wires fed through another hole drilled through the wood. Now this person installed a short jumper wire from the green ground screw to the neutral (silver) terminal of the outlet (I don't know why, but I assume that made the metal of the outlet casing and the metal cover live).

The outlet showed some damage due to arcing in the past and a portion of it appeared to have been blown off.

Question: How much of a fire and shock hazard do you think this was?