Reset button on used RAX120 not working

I purchased the net gear nighthawk rax120 on auction. I thought it was new but it was an Amazon return. No instructions in box. The app only works so far. The router name shows up on my phone but it’s locked and I need the password which I don’t have because I didn’t set it. I tried the default password and that doesn’t work. I have tried pressing the reset button for 20 seconds. I have tried the 30-30-30 reset to default settings but while the router shows up in my phone settings it is still locked and the default password does not work. And suggestions? I have successfully reset and used other routers I bought used. I tried just entering the IP address in my browser but that gets me nowhere. I’m reaching the end of my knowledge for further ideas. Is this one a lost cause?