nickzsh:

x_train = [ [[0], [1], [2], [3], [2], [1]], [[1], [2], [3], [2], [1], [0]], [[2], [3], [2], [1], [0], [1]], [[3], [2], [1], [0], [1], [2]], [[2], [1], [0], [1], [2], [3]] ]


I believe your x_train should look more like
x_train = ( [[[0]], [[1]], [[2]], [[3]], [[2]], [[1]]],
[[[1]], [[2]], [[3]], [[2]], [[1]], [[0]]],
[[[2]], [[3]], [[2]], [[1]], [[0]], [[1]]],
[[[3]], [[2]], [[1]], [[0]], [[1]], [[2]]],
[[[2]], [[1]], [[0]], [[1]], [[2]], [[3]]] )