Sorry for the delay in getting to your question.
Can you post the E-Nr number of the appliance please?
It should be on a label in the door recess.
Thanks for that.
On the Siemens dryer, F09 indicates a fault in the heating circuit.
Unplug the appliance.
You'll need Torx driver or bits for the screws.
Take the bulged cover on the rear off.
Look for the thermostat with a small button on it.
Press the button firmly to reset the thermostat.
Refit the cover.
Clean out the filter and condenser.
Clean out the condenser chamber.
Try the machine again.
If all is well, it will be working again.
If still no heat, you'll need to test the heater using a multimeter to see if it's open circuit.
Check it out, see what you find and get back to me if you need more help.
Hope this helps