The bottom oven does have a cleaning cycle on it.
Make sure the door is closed.
To set it turn the lower oven dial to clean.
Then turn the lower over thermostat which is the + and - knob.
As you turn the dial it should change between 1, 2 and 3. 1 being gentle 2 medium and 3 intensive.
Set it to which ever you want and wait a few seconds and it should kick in then.
Thats how you set the cleaning cycle on this. Try that and see if it works and let me know.
Strange, When you have it set to clean and you turn the lower oven dial is it just showing no on the display still then?
Try it this way instead.
Turn the main oven dial off.
Then turn the oven thermostat and see if it selects either 1, 2 or 3 cleaning levels
Then turn the oven dial to clean and see if it starts it then.
Ok im afraid its looking like a fault on the unit im afraid.
As the service info is showing it as having a cleaning cycle and thats the only way to start it just like the top oven.
So this is looking like the control unit is faulty if it wont select the clean cycle. Thats all it can be im afraid.
Sorry its not good news.
Nice one, Glad to hear thats sorted it and thanks for letting me know.
Hopefully it will be trouble free now :)
I see the question is still open here. Do you still need help on this?
If not then could you please rate the answer i gave and that will close the question on this.