Here is the situation:

Batter hits homerun with no runners on base and while rounding the bases he fails to touch 3rd base.

Now the defensive team makes an appeal at 3rd while the ball is still dead.

Fact 1) appeal plays can only be made when it is live ball

Fact 2) an appeal play is no play

Fact 3) the defensive team can not make a second appeal on the same runner at the same base

What is the ruling now?
It is quite obvious that the appeal is not sustained since we still have dead ball.
But can the defensive team give it another shot for a second appeal at 3rd base since an appeal is not a play and the appeal was made while the ball was dead???

Largo

No plays can be made while the ball is dead, and no appeals can occur when the ball is dead. Thus, this is no play and no appeal. The defense may appeal to get an out once the ball is alive.

In FED, the defense may appeal while the ball is dead. No action other than a verbal statement of what is being appealed is necessary.