Bosch DWB098E51B/04 Cooker Hood Extractor Fan Not Running

I have a Bosch DWB098E51B/04 Cooker Hood Extractor. On applying power, the machine displays the following sequence of numbers on the display: 1,3,1,7,1,0. I am not sure whether this is some kind of error code, but have been unable to find it anywhere on the web. All functions can be selected normally via the front panel buttons, lights (which work), fan speed and boost speed, which are displayed correctly, but the fan does not run. There is power reaching the control module board at the rear, but there does not seem to be any voltage on the motor connections from that board, even when, according to the display, the fan is switched on. A replacement control module board did not fix the problem.