Your A is not a matrix.
Try
In[30]:= Dimensions[A]
Out[30]= {6, 1, 6, 1}
To compute Eigenvalues you have to have a (square) matrix, that is a list of (one-dimensional) lists.
Look at
In[31]:= m = {{a, b}, {c, d}};
Dimensions[m]
Eigenvalues[m]
Out[32]= {2, 2}
Out[33]= {1/2 (a + d - Sqrt[a^2 + 4 b c - 2 a d + d^2]),
1/2 (a + d + Sqrt[a^2 + 4 b c - 2 a d + d^2])}
Why do you write at the beginning
F= { {q2}, ...
putting your variables (?) between { }? That makes q2 to a List.
In[34]:= FullForm[{q2}]
Out[34]//FullForm= \!\(\*
TagBox[
StyleBox[
RowBox[{"List", "[", "q2", "]"}],
ShowSpecialCharacters->False,
ShowStringCharacters->True,
NumberMarks->True],
FullForm]\)