How can I fix my Siemens Fan Oven model no hb53564fn?

The oven blows all the electricity in the house when it is turned on. The grill works fine. I tried looking for an element to change, having read that this was the most likely problem, but I can't find one, either from inside the oven or by removing the back or top casing.

The fan turns freely, doesn't seem to be a problem.

I've tried disconnecting fuses one at a time and the problem still persists.

When I disconnected what I thought was the condenser it there was a big bang and all the electricity tripped.

Any ideas would be really appreciated?

Cheers

Here are links to pictures of the oven
http://www.independentliving.co.uk/oven/IMG_4188.jpg
http://www.independentliving.co.uk/oven/IMG_4189.jpg
http://www.independentliving.co.uk/oven/IMG_4190.jpg