Group send a channel layer from outside consumer class

I have a process that when it gets a message it sends a command to a celery process. From there I would want to send back a message from the celery worker back to the backend telling it "Im done now you can continue". So can I send a group message to a channel layer from outside

edit should probably add some code example also:

consumer.py

async def startGame(self):
    if self.leader:
        songList = await self.getSongs()
        await self.downloadSongs(songList)

tasks.py

@shared_task
def downloadSongs(songList, room_group_name):
    from channels.layers import get_channel_layer
    print(room_group_name)
    for song in songList:
        if not os.path.isfile("./songfiles/" + song["song_id"] + ".mp3"):
            print("Downloading song: " + song["title"])
    channel_layer = get_channel_layer()
    print(channel_layer)
    async_to_sync(channel_layer.group_send)(
        room_group_name,
        {
            'type': 'startGameGroup',
        })
    print("Done sleeping")

consumer.py

async def startGameGroup(self, event):
    await self.send(text_data=json.dumps({
        "ContentType": "startGameGroup",
    }))

so when startGame in consumer run it calls a celery task called downloadSongs. From there it should send back a message to the backend saying that it is done and it can start the game