NMaximize[{10^700 Times @@ (a7[[;; 810]]), 0 < w11 < 1, 0 < w12 < 1,
0 < w21 < 1,
0 < w22 < 1, \[Lambda]11 > 0, \[Lambda]12 > 0, \[Lambda]21 >
0, \[Lambda]22 > 0, \[Alpha]11 > 0, \[Alpha]12 > 0, \[Alpha]21 >
0, \[Alpha]22 > 0, \[Beta]11 > 0, \[Beta]12 > 0, \[Beta]21 >
0, \[Beta]22 > 0}, {w11, w12, w21,
w22, \[Lambda]11, \[Lambda]12, \[Lambda]21, \[Lambda]22, \
\[Alpha]11, \[Alpha]12, \[Alpha]21, \[Alpha]22, \[Beta]11, \[Beta]12, \
\[Beta]21, \[Beta]22}, WorkingPrecision -> 20, MaxIterations -> 200]
0 < w21 < 1,
0 < w22 < 1, \[Lambda]11 > 0, \[Lambda]12 > 0, \[Lambda]21 >
0, \[Lambda]22 > 0, \[Alpha]11 > 0, \[Alpha]12 > 0, \[Alpha]21 >
0, \[Alpha]22 > 0, \[Beta]11 > 0, \[Beta]12 > 0, \[Beta]21 >
0, \[Beta]22 > 0}, {w11, w12, w21,
w22, \[Lambda]11, \[Lambda]12, \[Lambda]21, \[Lambda]22, \
\[Alpha]11, \[Alpha]12, \[Alpha]21, \[Alpha]22, \[Beta]11, \[Beta]12, \
\[Beta]21, \[Beta]22}, WorkingPrecision -> 20, MaxIterations -> 200]