Can you login on the Blizzard Battle.net website?
https://account.battle.net/login/en/Login Loop suggested remedies:
https://us.battle.net/support/en/article/19092"I'm stuck in a loop when I try to log into Battle.net because the login window keeps refreshing
After I enter my password I am sent back to the login window without any error"
If you have loading issues on the login page try the following:
If you are using a mobile device, try logging in on a PC, or vice versa
Clear your browser's cache and cookies
Try a different browser
Try using a different device/network
Reset your password
If you tried the above and you are still having trouble, please try again later or contact us.
And here:
https://us.battle.net/support/en/article/116234Common ProblemsThe Battle.net desktop app gets stuck in a login loopCan't log in to the Battle.net desktop app
Battle.net App stuck at the spinning Battle.net logo
The Battle.net App is unresposive
Reset your network devices to make sure your router hasn't become flooded with data.
If you're using a wireless connection, optimize your internet connection to rule out a connection issue.
Update your drivers and operating system to resolve any compatibility issues.
Release and renew your IP and flush your DNS to resolve any network conflicts.
Close all other applications to resolve software conflicts and free up resources.
Delete the Battle.net Tools folder to automatically rebuild outdated or corrupt files.
Advanced TroubleshootingCheck your network configuration to find any issues with your firewall, router, or port settings.
If you're using a VPN, try removing it.
Disable any proxies that may interfere with the login module.
Run a security scan to remove any viruses or malware infections.
Configure your security software's exception list to allow Blizzard applications to run.
Try creating a new administrator account to resolve permissions issues.
Your Windows Hosts file may contain incorrect entries. Check and reset any incorrect Hosts file entries.
Old firmware on your modem and router can cause issues with complex game connections. Visit the manufacturer's website for instructions on how to apply firmware updates.
Uninstalling and reinstalling the Battle.net App may resolve rare launcher issues.