If the fan is running and the indicator light is comming on then tis more then likely the heater element itself thats failed on this.
You need to empty the oven then remove the back panel.
Behind there you will see th heater around the fan blade. Have a look at the heater and see if theres a visable blow mark on there. If so then just replace the heater from there.
If it looks ok then you need to remove the heater and test it with a multi meter and again if faulty then it needs to be replaced.
But from the fault you describe this is more then likely a fault with the heater element. If you need anymore info just get back to me.