Finally decided to have a look at the SD card on my computer.
Issue appears to now be resolved by following part of the instructions on the above link.
So all I did was delete the LOOKDIR folder from the SD card and then put it back in the car.
Nice and easy in the end! As a precaution I didn't delete the folder but moved it off the SD card to the load back on if I broke the whole system.
Anyway, might be useful for anyone with the same issue.