Am facing login issue to trailhead, When i Click login, it take me to login.salesforce.com, After entering creadentials it take me to Trailhead Dev Org which is linkned to this id, I click ? icon and click go to trailhead, it takes me to trailhead without logging in, And I click Login, this loops repeats. facing this issue for past 2days.  Any help or workaround on this. 

I have a salesforce account - daniel.wymer@teradata.com - and get into endless loop and cannot reach Trailhead.  It seems like I have a Salesforce account, have established a password, but cannot login to Trailhead.