if you power the device off, then hold down the LED pushbutton as you plug it in, does the LED flash red a few times before going blank?
If it doesn't then you've not got the bootloader on the device. The first devices shipped without (to OWL Saints). I think we had some instructions for flashing the bootloader with the first firmware update but you might have missed that. Oh yes, here they are:
And if the bootloader isn't installed you'd have to force DFU mode:
If you're in London you can bring the pedal over to us in Finsbury Park, or ship it here, and we can do it for you.
If the LED does flash then the bootloader is working, and the device should now be in DFU mode.