Minesweeper grid representation + calculating neighbor-sums
One idea ... in your getSummedMap function, you could put all the +1, -1, 0's in a list of 2-tuples and get the Sum with one for loop, e.g. ...

neighbor_incs = [(-1, 0), (1, 0), (0, 1), (0, -1),  # Top + Bottom + Left + right
                 (-1, -1), (1, -1), (1, 1), (-1, 1), ] # diagonals

for x_inc, y_inc in neighbor_incs:
    Sum += paddedGrid[xIter + x_inc][yIter + y_inc]