What happens when a batter enters the box with an altered bat while a runner on first base steals second?

When a batter enters the box with an altered bat, it is considered a violation of the rules of the game. An altered bat is deemed illegal, and the use of such equipment results in immediate consequences once detected. In this scenario, the rules state that the ball is dead, meaning the play is halted at that moment. The batter is declared out due to the use of the altered bat, which ensures that the integrity of the game is maintained.

Furthermore, the runner on first base does not advance with this occurrence. Instead, he is required to return to first base since the play is called dead and the batter out. This approach serves as a deterrent against using illegal equipment and upholds fair competition. Therefore, in cases where an altered bat is used while a runner is actively attempting to steal a base, the appropriate ruling aligns with stopping the play and penalizing the batter.