Very sorry to hear it.
I would like to know it you can remove the power cable from NBN box (Arris black box), and leave it for like 5 min. It may clear any possible issue on the system if still on it.
Thanks for your quick reply,
It has been already escalate for troubleshooting by NBN. We will contact you for further update.
if you are still encountering technical difficulties, we are definitely happy to help.