The code prints else: at line 6 as invalid syntax.
The code to run as intended, as the code is(I think) properly indented and with syntax.
if guess_row == ship_row and guess_col==ship_col: print("Congratulations! You sank my battleship!") else: if guess_row not in range(5) or guess_col not in range(5): print("Oops, that's not even in the ocean.") else: print("You missed my battleship!") board[guess_row][guess_col]='X' print_board(board)