Belling - Formula Double oven - Yr 2000?

Heard a bang and the oven went dead. Reset fuses. To operate the oven, switch on at main power switch, the clock time requires setting to any time, ie away from 12:00. Then the oven fan switches on and lamp comes on. Even if the temp dial is off the fan and lamp are still working. The oven will operate by setting a desired temp. To switch off, you now need to power off at mains, as turning the temp dial to zero does not switch off anymore. Help.....