Hi Tony.
First of all welcome back, secondly, sorry but I am not to well up on modems/routers.
But:
Firmware updates, These I would avoid until all else fails, especially if it's not working to start with, but then again you probably could not update it anyway until it is working.
And even then I would still be a little hesitant to update something that is working okay.
Is there or have you tried to do a "Hard" re-set?
Is there a small hole where you can push "say a paper-clip" to re-set it to the factory settings?
If you think it may of been pre-configured by Demon, have you tried a combination of Demon as the user name and possibly "password or admin" as the password.
Failing those suggestion, hopefully some of the more informed people here will be able to help once they see your post.
Good luck.