hi, I´d tried it for 3 days, too. it´s a tough one
here´s your solution.

a) drop first 2 black balls right on the red square
b) drop next 2 black balls on the black ball in the middle
c) transform the red squares into red balls
d) transform the green squares into green balls
e) transform green balls into red balls
f) bring blue squares to explode
g) transform yellow squares into black squares
h) drop and rotate last column of black and red ball to explode the final obstacles

Did it? you did it.