Dead ball enforcement

[jjrye22]

Just over 2 1/2 minutes in the 4th quarter. A is using hurry-up offense.
3rd and 2 on B's 42. Dead ball offsides defense (with contact). We blow the play dead, and come up to the line.
After a good 5 seconds the QB from A launches the ball 30-35 yards deep to no one. I flagged it for delay of game (it gives him time to talk to his team while we retrieve the ball - I'll leave aside that he started talking about a free play, since we had blown it dead and he really launched the ball!)

My question (NCAA):
Since we had not had a chance to signal the offside, do the dead ball penalties cancel, replay 3rd down, or do we have A's 1st and 10 on B's 42 (5 forward, reset, 5 back, reset)?

Thanks,

James