GST Registration Canceled By Department

One of my friends applied Gst registration in March 2020. and doesn't commenced any business and never fill any return.

Its registration is canceled by Gst officials effective from Sept 2020 in March 2021.

After that, he never filled any quarterly return or GST 10 (Final Return).

Now, I will fill out all returns from March 2020 to September 2020. and fill gst 10(Final Return). Is any other action required or not? He doesn't want to register now but may need registration in the future.

So can you please let me know how much penalty he has to pay to close all the returns? Is it possible that he will get any relaxation from the penalty?

Thanks in advance for your reply and time.