Ошибка в функции пайтон ткинтер

Господа, имеется у меня такой код для крестиков ноликов. При нажатии кнопки "Заново" выдает ошибку:

Traceback (most recent call last):   File
"C:\Users\User\AppData\Local\Programs\Thonny\lib\tkinter\__init__.py",
line 1921, in __call__
    return self.func(*args)   File "C:\Users\User\Desktop\НЕ ЗАХОДИТЬ\крестики нолики.py", line 148, in restart
    restart_btn.destroy() NameError: name 'restart_btn' is not defined

Даже global 'restart_btn' не помог, хотя обычно помогал. Вот код:

import tkinter as tk

row1 = ['       ', '       ', '       ']
row2 = ['       ', '       ', '       ']
row3 = ['       ', '       ', '       ']

win = tk.Tk()
win.title('крестики-нолики')
win.geometry('300x435')

isnextx = False

def check_win_for_x():
    if row1[0] == row1[1] == row1[2] == 'x' or row2[0] == row2[1] == row2[2] == 'x' or row3[0] == row3[1] == row3[2] == 'x' or row1[0] == row2[0] == row3[0] == 'x' or row1[1] == row2[1] == row3[1] == 'x' or row1[2] == row2[2] == row3[2] == 'x' or row1[0] == row2[1] == row3[2] == 'x' or row3[0] == row2[1] == row1[2] == 'x':
        return True 
    else:
        if row1[0] == row1[1] == row1[2] == 'o' or row2[0] == row2[1] == row2[2] == 'o' or row3[0] == row3[1] == row3[2] == 'o' or row1[0] == row2[0] == row3[0] == 'o' or row1[1] == row2[1] == row3[1] == 'o' or row1[2] == row2[2] == row3[2] == 'o' or row1[0] == row2[1] == row3[2] == 'o' or row3[0] == row2[1] == row1[2] == 'o':
            return False
        else:
            return None
def end_game():
    if check_win_for_x() == True:
        label_win = tk.Label(win, text='победа крестиков', font = ('Arial', 30)).place(x = 0, y = 300)
        restart_btn = tk.Button(text = 'заново', font = ('Arial', 27), command = restart).place(x = 0, y = 360)
    else:
        if check_win_for_x() == False:
            label_lose = tk.Label(win, text='победа ноликов', font = ('Arial', 30)).place(x = 0, y = 300)
            restart_btn = tk.Button(text = 'заново', font = ('Arial', 27), command = restart).place(x = 0, y = 360)
def changetextbtn1():
    global isnextx
    if isnextx:
        btn1.config(text='❌', state='disabled', font = ('Arial', 45))
        isnextx = False
        row1[0] = 'x'
    else:
        btn1.config(text='⭕', state='disabled', font = ('Arial', 45))
        isnextx = True
        row1[0] = 'o'
    end_game()

def changetextbtn2():
    global isnextx
    if isnextx:
        btn2.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row1[1] = 'x'
    else:
        btn2.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row1[1] = 'o'
    end_game()

def changetextbtn3():
    global isnextx
    if isnextx:
        btn3.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row1[2] = 'x'
    else:
        btn3.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row1[2] = 'o'
    end_game()

def changetextbtn4():
    global isnextx
    if isnextx:
        btn4.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row2[0] = 'x'
    else:
        btn4.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row2[0] = 'o'
    end_game()

def changetextbtn5():
    global isnextx
    if isnextx:
        btn5.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row2[1] = 'x'
    else:
        btn5.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row2[1] = 'o'
    end_game()

def changetextbtn6():
    global isnextx
    if isnextx:
        btn6.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row2[2] = 'x'
    else:
        btn6.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row2[2] = 'o'
    end_game()

def changetextbtn7():
    global isnextx
    if isnextx:
        btn7.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row3[0] = 'x'
    else:
        btn7.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row3[0] = 'o'
    end_game()

def changetextbtn8():
    global isnextx
    if isnextx:
        btn8.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row3[1] = 'x'
    else:
        btn8.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row3[1] = 'o'
    end_game()

def changetextbtn9():
    global isnextx
    if isnextx:
        btn9.config(text='x', state='disabled', font = ('Arial', 45))
        isnextx = False
        row3[2] = 'x'
    else:
        btn9.config(text='o', state='disabled', font = ('Arial', 45))
        isnextx = True
        row3[2] = 'o'
    end_game()
def restart():
    global btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9
    global restart_btn
    btn1.destroy()
    btn2.destroy()
    btn3.destroy()
    btn4.destroy()
    btn5.destroy()
    btn6.destroy()
    btn7.destroy()
    btn8.destroy()
    btn9.destroy()
    restart_btn.destroy()
    btn1 = tk.Button(win, text='', command=changetextbtn1)
    btn1.place(width=100, height=100, x=0, y=40)
    btn2 = tk.Button(win, text='', command=changetextbtn2)
    btn2.place(width=100, height=100, x=100, y=40)
    btn3 = tk.Button(win, text='', command=changetextbtn3)
    btn3.place(width=100, height=100, x=200, y=40)
    btn4 = tk.Button(win, text='', command=changetextbtn4)
    btn4.place(width=100, height=100, x=0, y=140)
    btn5 = tk.Button(win, text='', command=changetextbtn5)
    btn5.place(width=100, height=100, x=100, y=140)
    btn6 = tk.Button(win, text='', command=changetextbtn6)
    btn6.place(width=100, height=100, x=200, y=140)
    btn7 = tk.Button(win, text='', command=changetextbtn7)
    btn7.place(width=100, height=100, x=0, y=240)
    btn8 = tk.Button(win, text='', command=changetextbtn8)
    btn8.place(width=100, height=100, x=100, y=240)
    btn9 = tk.Button(win, text='', command=changetextbtn9)
    btn9.place(width=100, height=100, x=200, y=240)
    row1 = ['       ', '       ', '       ']
    row2 = ['       ', '       ', '       ']
    row3 = ['       ', '       ', '       ']
def place_buttons():
    global btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9

    btn1 = tk.Button(win, text='', command=changetextbtn1)
    btn1.place(width=100, height=100, x=0, y=0)
    btn2 = tk.Button(win, text='', command=changetextbtn2)
    btn2.place(width=100, height=100, x=100, y=0)
    btn3 = tk.Button(win, text='', command=changetextbtn3)
    btn3.place(width=100, height=100, x=200, y=0)
    btn4 = tk.Button(win, text='', command=changetextbtn4)
    btn4.place(width=100, height=100, x=0, y=100)
    btn5 = tk.Button(win, text='', command=changetextbtn5)
    btn5.place(width=100, height=100, x=100, y=100)
    btn6 = tk.Button(win, text='', command=changetextbtn6)
    btn6.place(width=100, height=100, x=200, y=100)
    btn7 = tk.Button(win, text='', command=changetextbtn7)
    btn7.place(width=100, height=100, x=0, y=200)
    btn8 = tk.Button(win, text='', command=changetextbtn8)
    btn8.place(width=100, height=100, x=100, y=200)
    btn9 = tk.Button(win, text='', command=changetextbtn9)
    btn9.place(width=100, height=100, x=200, y=200)
place_buttons()
win.mainloop()