ending the half on a B penalty.....

[northindyref]

Please check the casebook on page 25, 3.3.3 situration e.
With the ball at B's 1-yard line and 12 seconds remaining in the game, A1 advances to the 1/2-yard line. After the ball is dead, B1 fouls. The clock is stopped with five seconds remaining in the game. The clock is restarted when the ball is declared ready for play. Before A can snoap the ball, time expires. Ruling: The game is ended. There is no extension of the period for an untimed down, unless there is acceptance of the penalty for a foul which occurred during the down. However, if the referee judges B1 committed the foul to consume time, he shall delay starting the clock until the snap.