Simple question, but can't find answer

[Ump180]

I know that the answer is simple, but I can't seem to get a consensious:

Runner on second and third, outs don't matter. Grounder to short, fields clean and throws wide of first. F1 nocks the ball down, rolling (but not going to go out of play) 1st base coach (a) in box or (b) out of box kicks the ball out of play.

Who advances/is called out? Basiclly, what does the umpire do? (FYI: when this actually happend, the umps missed the kick so played is as if the ball went in off the throw)