Yikes! That's exactly the sort of experience a good BR should be improving! Well don't let that deter you. I feel there's a randomness to the process that defies logic sometimes. I went thru many interview loops myself when changing from Amazon to Google. In some I did great, in some I did not. I had the same level of preparedness on all. But there are so many external factors. Even Google, I interviewed here 3 times in 12 years! (first loop: yes, but went with Amazon; second loop: nope!; third loop: yes and I went with Google). So moral of the story: keep trying! :)