You have made LOTS of mistakes. Be VERY careful with your negative signs!

$\displaystyle \begin{align*} - \left[ \frac{\sqrt{2}}{2} - \left( - \frac{\sqrt{2}}{2} \right) \right] ^2 &= - \left( \frac{\sqrt{2}}{2} + \frac{\sqrt{2}}{2} \right) ^2 \\ &= - \left( \frac{2\sqrt{2}}{2} \right) ^2 \\ &= -\left( \sqrt{2} \right) ^2 \\ &= -2 \end{align*}$

See if you can fix your second bracket - you have similar mistakes there too...