Okay just finished installing the Android APP to phone as the old Authenticator is no longer supported.
When I opened the Battle.net APP it was asking for a password. After inputting the password the screen flashed and opened another page requesting password, so basically seemed to be stuck in a loop.
The FIX is check which browser on your phone is the default and change it.
For me I was using AVAST ONE BROWSER , changing back to Chrome fixed the issue.