Damaged Bat Situation

 
With no outs and the bases loaded, the batter (B1) hits a base-clearing double. After the play ends, the plate umpire notices that the bat has a big dent in it. What does the umpire do now?
 
1. Does this illegal bat have any impact on the bases-clearing double?
 
2. What would the plate umpire do if the plate umpire noticed the dent during B1's at-bat (before the bases-clearing double)?
 
Call
In NF, when a batter enters the batter's box with an illegal bat, he is declared out. If an illegal bat is discovered immediately after it has been used to put the ball in play -- and the umpire judges that the damage was done (or could have been done) during the course of the play -- then the bat is removed from the game without penalty.
 
In the play below, when the dent is discovered after the bases-clearing double, the bat is taken out of play without any other penalty,
 
In situation #2, since the illegal bat was discovered while B1 was still at bat, B1 is immediately out (NF 7-4-1a and Casebook 1.3.5D).