Well, B gained very little with the L’s error. Team A would have had to snap by 15 seconds. With luck, B could have prevented A from earning a new series, and have taken possession with some 5 to 10 seconds remaining, with a chance to attempt a field goal to tie the game.
As it is, the play clock will be set to 25 seconds, and both the play clock and game clock will start on the Referee’s signal. Team A can let the game clock run down to 5 seconds, snap the ball, and run around for 5 seconds and win the game.
And then a little ‘re-training’ with the Line Judge.