My code from tkinter counter crashes on execution. I am not sure why

I copied this code to try to make a countdown app in tkiner. Whenever I run the code and click the generated button, it just just keeps loading, and I have to force quit. I am wondering if there is something wrong with this code? Everything seems to generate fine, the only problems seems to be the button click and execution.

import time
from tkinter import *
from tkinter import messagebox

root = Tk()
root.geometry("300x250")
root.title("Time Counter") 

hour=StringVar()
minute=StringVar()
second=StringVar()

hour.set("00")
minute.set("00")
second.set("00")

hourEntry= Entry(root, width=3, font=("Arial",18,""),
                 textvariable=hour)
hourEntry.place(x=80,y=20)

minuteEntry= Entry(root, width=3, font=("Arial",18,""),
                   textvariable=minute)
minuteEntry.place(x=130,y=20)

secondEntry= Entry(root, width=3, font=("Arial",18,""),
                   textvariable=second)
secondEntry.place(x=180,y=20)

def submit():
    try:
        temp = int(hour.get())*3600 + int(minute.get())*60 + int(second.get())
    except:
        print("Please input the right value")

    while temp >-1:
        mins,secs = divmod(temp,60) 


    hours=0
    if mins >60:
        hours, mins = divmod(mins, 60)

        hour.set("{0:2d}".format(hours))
        minute.set("{0:2d}".format(mins))
        second.set("{0:2d}".format(secs))


        root.update()
        time.sleep(1)

        if (temp == 0):
            messagebox.showinfo("Time Countdown", "Time's up ")

        temp -= 1

btn = Button(root, text='Set Time Countdown', bd='5',
             command= submit)
btn.place(x = 70,y = 120)

root.mainloop()