Hi, this morning my WMA35 did exactly the same thing.
The PCB board had not just burnt as you described but i also noticed some copper tracks had popped off of it. That is not a good sign, it means a huge amount of current had shorted on the tracks.
I resoldered the broken tracks and went for another run of the machine. After 10 seconds of running i heard a bang and it had failed again! Every component on the board has been checked and seems to be ok so the problem seesm to lie further into the machine. The second attempt produced another broken track on the board but in another place, this time on a path that leads to the motor.
Unfortunately i could not check the motor brushes because i do not have the special socket to remove them with but tommorow i will get it off to check the brushes. I suspect that something is going wrong in the brush section.
The machine is about 4 years old so brushes are due replacement but exploding is not the preferred method of communication on that matter.
Chris
Chris
September 2009