Hi, the question I'm struggle with is (z^2 + 1)^3 = -1

I have to find all the solutions for this question and the answer should be in Cartesian form

I start the question by powering both side by 1/3

thus the equation become

Z^2 + 1 = -1^(1/3)

since i^2 = -1

Z^2 +1 = (i^2)^(1/3)

from here I sub in Z = X + iY

so the equation become

X^2 + 2XYi - Y^2 = (i^2)^(1/3) + 1

I'm pretty much stuck now and unable to continue the question. Can you guy tell me how to continue this question and get the solution in cartesian form?

(I have a feeling that I did something wrong in the step above