BAXI BERMUDA CENTRAL HEATING?

MY DAUGHTER HAS A GROUND FLOOR FLAT WITH A BAXI BERMUDA HOT WATER / CENTRAL HEATING SYSTEM . I TOOK THE RADIATORS OFF TO HAVE THE WALLS REPLASTERED . WHEN REFITTED & BLED THE BOILER FIRED UP FOR A SHORT PERIOD THEN WENT OUT , LEAVING JUST THE PILOT BURNING . IVE TRIED RE BLEEDING & TAKEN THE BUNG OUT OF THE TOP OF THE BIOLER TO BLEED THAT BUT ALTHOUGH THE BURNER FIRED UP FOR A SHORT PERIOD AGAIN IT SOON WENT OUT . COULD THIS BE AIR STILL IN THE SYSTEM . IM NO EXPERT ON HEATING BUT AM REASONABLY HANDY