I'm making a program that Identifies if a blank tile exists or not. I already have a code in my 2d array which is

arr2 = [['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' 'E' 'A' '#' 'L' 'E' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' 'P' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' 'P' 'E' 'A' 'K' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' 'L' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' 'E' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']['0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0' '0']]

I want to replace the # which is I labeled for the blank tile into one of the letters in the alphabet(A-Z). I already made a code that replaces the blank tile.

for i in arr2:for j in i:if j == '#':i = [j.replace('#', 'A')]

But for some reason it is still a # not an A. How do I replace the #(blank tile) in the given array into an alphabet? Also, how do I make a pop-up message so that players can just type an alphabet to replace for the # which is the blank tile?

You have to enumerate your array to change the value at a specific index.

for i, row in enumerate(arr2):for j, cell in enumerate(row):if cell == '#':arr2[i][j] = 'A'