Other then the clean filter light flashing are any of the lights on the top lit at the same time?
If so which ones?
Ok try this and it should reset the control unit.
Turn the dial to off.
Then turn it to 6 oclock posistion.
Press the start button 3 times.
Turn the dial 1 click clockwise and press the start button 3 times again.
Then turn the dial to off.
Now turn it back on again and see what happens from there and let me know.
Ok if the control unit isnt resetting by doing the above then try and unplug it for 20 minutes. Remove the plug from the socket completey and see if this clears it.
But if its still the same after that then it can only be the control board at fault here as if you cannot reset it then that can only be down to a board fault nothing else im afraid on this.
No worries, Your very welcome.