Python tkinter password strength checker gui

I'm trying to create a password strength checker gui that checks a password for length(over 8 characters) lowercase and uppercase letters, numbers and special characters and then tells you what level it is, weak, strong etc.... It then creates an md5 hash and displays this, then you can store this hash in a text file. Then re enter the password again and verify from the text file (havent done any code for this yet).

I've managed to achieve the strength check, hash generation, log to a file....I think. Although if no password is entered i would like the code to return 'Password cannot be blank', but it doesnt seem to work in a gui. The same code works from within a shell. The code also never returns 'Very Weak' as a strength, even when only 3 characters are used as a password.

Here is my code so far:

from tkinter import *
import hashlib
import os
import re

myGui = Tk()
myGui.geometry('500x400+700+250')
myGui.title('Password Generator')
guiFont = font = dict(family='Courier New, monospaced', size=18, color='#7f7f7f')


#====== Password Entry ==========
eLabel = Label(myGui, text="Please Enter you Password:   ", font=guiFont)
eLabel.grid(row=0, column=0)
ePassword = Entry(myGui, show="*")
ePassword.grid(row=0, column=1)



#====== Strength Check =======


def checkPassword():
    strength = ['Password can not be Blank', 'Very Weak', 'Weak', 'Medium', 'Strong', 'Very Strong']
    score = 1
    password = ePassword.get()

    if len(password) < 1:
        return strength[0]

    if len(password) < 4:
        return strength[1]

    if len(password) >= 8:
        score += 1

    if re.search("[0-9]", password):
        score += 1

    if re.search("[a-z]", password) and re.search("[A-Z]", password):
        score += 1

    if re.search(".", password):
        score += 1

    passwordStrength.set(strength[score])

passwordStrength = StringVar()
checkStrBtn = Button(myGui, text="Check Strength", command=checkPassword, height=2, width=25, font=guiFont)
checkStrBtn.grid(row=2, column=0)
checkStrLab = Label(myGui, textvariable=passwordStrength)
checkStrLab.grid(row=2, column=1, sticky=W)

#====== Hash the Password ======


def passwordHash():
    hash_obj1 = hashlib.md5()
    pwmd5 = ePassword.get().encode('utf-8')
    hash_obj1.update(pwmd5)
    md5pw.set(hash_obj1.hexdigest())

md5pw = StringVar()
hashBtn = Button(myGui, text="Generate Hash", command=passwordHash, height=2, width=25, font=guiFont)
hashBtn.grid(row=3, column=0)
hashLbl = Label(myGui, textvariable=md5pw)
hashLbl.grid(row=3, column=1, sticky=W)


#====== Log the Hash to a file =======


def hashlog():
    loghash = md5pw.get()

    if os.path.isfile('password_hash_log.txt'):
        obj1 = open('password_hash_log.txt', 'a')
        obj1.write(loghash)
        obj1.write("\n")
        obj1.close()

    else:
        obj2 = open('password_hash_log.txt', 'w')
        obj2.write(loghash)
        obj2.write("\n")
        obj2.close()

btnLog = Button(myGui, text="Log Hash", command=hashlog, height=2, width=25, font=guiFont)
btnLog.grid(row=4, column=0)

#====== Re enter password and check against stored hash ======
lblVerify = Label(myGui, text="Enter Password to Verify:   ", font=guiFont)
lblVerify.grid(row=5, column=0, sticky=W)

myGui.mainloop()

Any help would be much appreciated. Thanks.