can't access mifi admin after changing login credentials

I decided to change my mifi’s admin username and password. after that, i tried logging back to it and just realized that I can’t log back into my admin mifi account using the new details i created. Please how do I go about this?

please i just bought this the previous saturday and i am reviewing the object before i will post it on my social handles, blogs, groups, pages, channels and my websites.

this is posing to be a setback for the review as you won't like this issue to be added as negative review in my user experience with this item.