x x x x x  | 'x's are already flipped or worthless (can only be voltorb or one)
x ? x ? x  | In the second and fourth rows, 2 points and
x x x x x  | 1 voltorb are left undiscovered
x ? x ? x  | Same for second and fourth column
x x x x x  | Possible answers :
           
x x x x x
x • x 2 x  | ('•'s are voltorbs)
x x x x x
x 2 x • x
x x x x x

x x x x x
x 2 x • x
x x x x x
x • x 2 x
x x x x x