Don't login.
Use the power icon on the login screen, while holding down the Shift key on your keyboard to choose Restart.
That should allow you some control during the restarting process to choose the Advanced Troubleshooting Options to use Startup Settings to boot the system into Safe Mode and or Safe Mode with networking.
So when you manage to navigate to the appropriate screen try #5 from the selection options to reboot the system into Safe Mode with Networking.
Does the computer still loop to multiple login screens when you do it that way?
IF not, then let it remain in Safe Mode with Networking for a half hour or so then use the normal method of restarting and start it normally and see if it is OK in normal mode.