I cannot update a variable from get_node()

Archive
1
:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By purpleGorgon 
if event is InputEventMouseButton: 		
     if event.button_index == BUTTON_LEFT and event.pressed: 			
          var board = get_node("/root/Board") 			
          board.mat[0][0] = 4 			
          board._process(1) 			
          print(board.mat[0])


extends Node2D
var mat = [
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
[0,1,0,2,3,4,5,0,1,0,2,3,4,5],
]

 func _draw():
for i in range(0, len(mat)):
	for j in range(0, len(mat[0])):
		var color = "#ff0000"
		if mat[i][j] == 1:
			color = "#00ff00"
		if mat[i][j] == 2:
			color = "#00ff00"
		if mat[i][j] == 3:
			color = "#ddaadd"
		if mat[i][j] == 4:
			color = "#eeee00"
		if mat[i][j] == 5:
			color = "#cc00cc"
		
		draw_rect(Rect2(20*j, i*20, 20, 20), color)

func _process(_delta):
update()

I am unable to update my board variable mat to see the color change.

EDIT:
I was creating 2 instances of board it seems. Hiding one of them fixes the issue.