everything here is very simple:
If the ritual is said, blow out a candle or pay after the commission of certain acts in the ritual means to extinguish the candle and it can not be a bad thing.
If the text of the ritual does not say that it is necessary to pay off the candle, the candle on the rules must always burn until the end!
If you accidentally blew out the candle, it means a mistake in the ritual, and it has to be redone, because the with high probability we can say that the ritual will fail and the result will not be.
In addition. if you accidentally blew out the candle, this may mean that the man on whom the ritual is performed magical protection from impacts. and extinguished the candle signals this