Nothing is changed by 53...Bb2 54.Kh3.

There is no defence against Nf3-h4.

One can see the most beautiful and accurate mating nets in endgame studies. It seems that White clearly has insufficient resources to win this position, but by exploiting mating possibilities and the fact that he has the move, he manages to win:

1...Kf5 2.Qd3++–.

Otherwise, the queen is lost. But what now?

Drawing the king into the trap.

5...Kxh4 6.Bf6#; 5...Kf5 6.Qf6+ Ke4 7.Qd4+ Kf5 8.Qd3++–.