what light is flashing? on the charger? or on the bdi?
chances are there is a battery fault OR the battery voltage is too low and the charger is erroring out because of it.
the charger has to see a certain voltage before it will even try to charge, if the voltage is too low it will trigger a fault and make the LED flash a code.
Watch the flashing light and see if it pauses, count the number of flashes between the pause.