whats wrong with my Worcester Danesmoor 12/14?

got up this morning to find my danesmoor on lockout. Rads were cold so had been off couple of hours i assume.
sorted it out, got it running, a normal noise of it about to start (priming?) happened for about 3 seconds, (normally kicks in at this point and fires) but small puffs of smoke - smelling like burnt fuel came out of the front from a small black cyclindrical box down at the bottom of the boiler. it has the markings W and P on it and a a fan/pump icon and te writing sentec? now we tried starting it again and the same happened. Im not sure when the boiler had been serviced, we have just bought the house and just got fuel delivered in the last 2 weeks.We will be removing it shortly - we are doign a renovation. can anyone help? thanks