Image not printing to screen using 'Blit' Pygame

I am trying to make an Undertale like game in python - However I have a problem. When I try to 'blit' an image to the screen it doesn't show. I am 'blitting' a heart and I have rescaled it to an appropriate size in a 3rd party program.

import pygame  # Imports Pygame Library
import keyboard  # Imports Keyboard Library

# Defining Image Components
undertale_logo_ico = pygame.image.load('Undertale_Logo.ico')
Soul_Heart_Red = pygame.image.load('UndertaleHeart.png')


# Define Key-presses
def movement(key_pressed):
    if key_pressed == 'right':
        print('Right')
    elif key_pressed == 'left':
        print('Left')
    elif key_pressed == 'up':
        print('Up')
    elif key_pressed == 'down':
        print('Down')
    else:
        print('Not registered key')


# Execute Key Presses:
keyboard.on_press_key("right arrow", lambda _: movement('right'))
keyboard.on_press_key("left arrow", lambda _: movement('left'))
keyboard.on_press_key("up arrow", lambda _: movement('up'))
keyboard.on_press_key("down arrow", lambda _: movement('down'))
keyboard.on_press_key("d", lambda _: movement('right'))
keyboard.on_press_key("a", lambda _: movement('left'))
keyboard.on_press_key("w", lambda _: movement('up'))
keyboard.on_press_key("s", lambda _: movement('down'))

# Display Window Configuration
# area = screen.get_rect()
screen = pygame.display.set_mode((0, 0), pygame.FULLSCREEN)
background_colour = (0, 0, 0)
(width, height) = (300, 200)
pygame.display.set_caption('Game 1')
screen.fill(background_colour)
pygame.display.set_icon(undertale_logo_ico)
pygame.display.flip()

# Drawing Player

screen.blit(Soul_Heart_Red, [0, 0])

# Closing Script
running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

The blit() is near the bottom of the code.

You have to update the display after blit:

screen.blit(Soul_Heart_Red, [0, 0])
pygame.display.flip()                  # <---