It loops forever and doesn't let me login.

Here are pictures of the loop after it says for an instance connection is secure, it reloads the 1st picture infinitely.

What security software are you running? I was able to create an account and login with no issues. see screenshot

Try the option Forget About This Site, but make sure you know the login info. https://support.mozilla.org/en-US/kb/remove-websites-address-bar-suggestions

You could try troubleshoot mode (or a new profile).

https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration)

https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_start-the-profile-manager-when-firefox-is-closed

What security software are you running? I was able to create an account and login with no issues. see screenshot

Kaspersky, recent update for firefox, and nothing else changed really, firefox just updated and then on a reboot the site and samsung login website too https://account.samsung.com/membership/intro seems to loop on a login screen.

Wait weird thing now the Samsung site works and doesn't loop, but nexus still loops when checking security.

You could try troubleshoot mode (or a new profile). https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration) https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles#w_start-the-profile-manager-when-firefox-is-closed

Have to say refreshing firefox worked and it fixed the problem with Nexus and other sites. Thanks m8! Help>more trouble shooting information> Then refresh firefox on the right, it saves bookmarks and addons I believe as I didn't need to download them again, but it messed up my theme and went back to default. All bookmarks came back though had to re-pin all the tabs.