Unfortunately, I’m at a loss about what could cause the issue you’re having. All I can recommend is the usual try-another-browser, clear-your-cookies, … (and so and so forth)
For reference, after I login, I see this:
As you may be able to tell, I was actually able to get to the quiz, where I got a perfectly failing score. That’s something worth noting… Don’t hit the Start Quiz button unless you really want to take the test!
I clicked Start Quiz thinking I could just take a look, not answer any questions, close the tab, and everything would be hunky dory. Not so much. Even though I didn’t click on anything in the Quiz window, when I closed the browser tab, it calculated my score and gave me 0 our of 45. Considering how much I knew at the time I did that, I think I did better than I deserved, lol.
Sorry I’m not able to help beyond that. If I think of something, I’ll let you know.
Meantime, Good Luck! (With your login issue and with getting your Certification )