AirCard 815S (AT&T)

I have bought a Unlocked Netgear AirCard 815S (AT&T) and I have service through cricket. The service works and will send me to the login page to acces the data. The admin password for the login page “attadmin” for AT&T will not work and I cannot do a factory reset on the device because it is in READ ONLY mode. What can I do? when I contact the provider I just get the run around and told to use different browsers. I have done everything I can do so now I’m reaching out looking for other solutions???