I was also confused at the beginning but there is no error in this test.

For example, your two solutions have a common "!" (the first cell in the 3rd row). You can safely open that cell and continue according to the result. When you open it, the number you get will eliminate some of those possibilities.

In the 17th test, after the following case, there are more than one solutions.

0 1 1 2 1 1 0 0 0 1 1 2 2 2 2 x 1 0 0 0
0 1 x 2 x 1 0 0 0 1 x 3 x x 3 2 1 0 0 0
0 1 1 2 1 1 0 0 0 1 2 x 3 3 x 1 0 0 1 1
0 0 0 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 1 x
0 0 0 1 x 1 0 0 0 0 0 0 0 0 0 0 0 1 2 2
0 1 1 2 1 1 0 0 0 0 0 0 0 0 0 0 0 1 x 1
0 1 x 1 0 1 1 1 0 0 0 0 0 1 1 1 0 1 1 1
0 1 1 1 0 1 x 2 2 2 1 0 0 1 x 2 1 1 0 0
0 1 1 1 0 1 1 2 x x 1 0 0 1 1 2 x 1 0 0
0 1 x 1 0 0 0 1 2 2 1 0 0 0 0 2 2 2 0 0
0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 1 x 2 1 0
0 1 1 1 0 0 0 0 0 1 1 1 0 0 0 1 2 x 1 0
0 1 x 1 0 0 0 0 0 1 x 2 1 1 0 1 3 3 2 0
1 2 1 1 0 0 0 0 0 1 1 2 x 1 0 2 x x 1 0
x 1 0 0 0 0 0 0 0 0 0 1 1 1 0 2 x 4 3 2
1 2 1 1 0 0 0 0 0 0 0 0 0 0 0 1 1 2 x x
1 2 x 1 0 0 1 2 3 2 1 0 1 1 1 0 0 1 2 2
1 x 3 3 1 1 1 x x x 1 0 2 x 2 0 0 0 0 0
1 2 x 2 x 1 2 3 4 2 1 0 2 x 3 1 0 0 0 0
0 1 1 2 2 2 2 x 1 0 0 0 1 2 x 1 0 0 0 0
0 0 0 0 1 x 2 1 1 0 0 0 1 2 2 1 0 0 0 0
0 0 0 0 1 1 1 0 0 0 0 0 1 x 2 1 0 0 0 0
0 0 0 0 0 0 0 1 2 2 1 0 1 2 x 1 0 0 0 0
1 1 1 1 1 0 0 1 x x 2 1 1 1 2 2 2 1 1 0
x 2 3 x 2 0 0 1 2 2 2 x 1 0 1 x 2 x 2 1
2 ? ? x 2 0 0 0 0 0 1 2 2 1 1 1 2 1 2 x
? ? 3 3 2 1 0 0 0 0 0 1 x 1 0 0 0 1 2 2
? ? ? 2 x 1 0 0 0 0 0 1 1 1 0 0 0 1 x 1
? ? ? 2 1 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1

There are 3 mines left and 10 ? left; all in the bottom-left corner:

1 1 1 1 1
x 2 3 x 2
2 ? ? x 2
? ? 3 3 2 
? ? ? 2 x 
? ? ? 2 1

One solution is

1 1 1 1 1
x 2 3 x 2
2 X ? x 2
? ? 3 3 2
X ? X 2 x
? ? ? 2 1

Another solution is

1 1 1 1 1
x 2 3 x 2
2 ? X x 2
? X 3 3 2 
? ? ? 2 x 
? ? X 2 1

So, the return value should be "?"