Fumble ?

[Patton]

The result of the play would be a touchback since A's fumble was the force that put the ball in the endzone. However, did B muff the fumble out of the endzone, or did he illegally bat it out? If you judge that he illegally batted it, the penalty would be assessed half the distance to the goal from the end of the run or previous spot (depending on where the fumble occured) and replay the down.