Ongoing issues with Nighthawk M1 - Telstra

Hi there,

I purchased a Nighthawk M1 that was brand new off ebay.  It worked quite well for a good 2 months and now I have the following issues.

On Telstra using mobile data pre-paid.

Issues:

1. There was a message stating "mobile broadband disconnected", I could still see my Telstra data remaining screen but couldn't access the internet.  I called Telstra and they said nothing has changed and the SIM is active - I confirmed this by putting the SIM in another router and it works fine (netgear aircard).  So I factory reset the device using both the admin panel and by pressing a PIN into the reset area at the back. Since resetting I have now lost the "remaining data screen".

Here's a link to the issue I'm having

2. For some reason sometimes when I turn on the modem it powers itself off.

I'm in a bit of a bind; while this router has warranty until 2019, I can't request a replacement from Telstra - as the asset was in another name.  I'm currently in talks with the ebay seller to fix this. 

In the meantime has anyone had any similar issues and able to help?

Thanks in advance