Problem solved!
The Bosch guy came and looked at the oven. He took the top off and checked the voltage across the power lines and the terminal block. "You've 240 volts between the red and the white wires!" My response was alarm, as you can imagine. All I had ever measured there was 120. He brought me over to look, and by then there was 0 volts between red and white. 240 red to black, 0 black to white, 0 red to white, take a second to sneeze, and then 240 red to white.
The tech guy bailed on me, but took a check for $80 with him.
I took the male plug apart AGAIN, with some idea what to look for this time and sure enough, the green ground wire was clearly under the screw connected to the neutral lug. On the other side of the screw, were it was harder to see, the white wire had come loose and was floating around, connecting with the neutral lug, or open, or laying against the black connector, depending on how you moved the cord around.
It was my error, I just didn't take a thorough enough look around when I looked at the connections.