Simens HB96540GB/01?

Good morning all,

Wondering if anyone can advise on a problem I have encountered on the above oven.

I removed the control panel situated above the top oven to see why two of the oven controls were not illuminating.
I ascertained that the rotary switches were broken internally, so refitted the control panel for the time being.

However, when I turned the power back on, the cooling/vent fan now runs continuassly.

I rechecked to see if I had disturbed something inside to no avail.

Any help would be much appreciated.

Jon