apologies if this has been covered before, but I pulled in to my local petrol station the other day to fill up, and to my surprise I couldn't open the fuel flap.
I managed to pull the cover off ( by mistake ) but no luck getting in to it. So I went home looked in the handbook and found a 10amp fuse had blown. Replaced it and the flap opened.
The morale of the story is always keep the handbook in the car........ :oops:

If it happens again, you may need to change the flap motor....
A latent problem into the CJB software makes the motor to overwork and this, in time, leads to its failure.
But fortunately, of course, the first to fail is the fuse....