e36 electrical gremlin

My e36 "M3"(not actually an M3) electrically crapped out on me on Monday. 298 miles into a 299 mile roadtrip the car cut out. I was decelerating into an intersection and it cut off. No electricity. I pulled over and cycled the key. No power. Being that it was raining heavily and I don't have a garage I had it towed to my local German car mechanic.

The mechanic found that the car is getting power to the front distribution block(jump start connection) but there is no power making it to the fuse box.

If anybody knows their way around an e36, where should we be looking? I'm guessing it's just going to be a game of tracing wires but any pinpointing would be appreciated.