OMG did you get the first-round invitation??? Congrats!!!!!!
Basically it's all about familiarizing yourself with the "case interview" format. Even business students are not too familiar with that as well. Please feel very free to go up to any online sources to know more about it, and there are so many mock interview / demo / interview walkthroughs as well. One key point of that should be how you communicate with the interviewer to get some extra "information" other than those you learnt from the case brief.
Even try to at least skim through all of the video preparation materials MBB provided online (eg from their career sites, YouTube, etc) to see if you can gain any insights from that. Example: https://www.youtube.com/watch?v=nGzYzq3Wsos
Some famous YouTube channels did provide in-depth explanations on how to deal with different types of questions, eg:
- Management Consulted
- Hacking the Case Interview (https://www.youtube.com/watch?v=akdsoi71R6U)
Wish the above can help! After you had the interview, please do help us and our other users by sharing your interview experience and the content of it via: http://bit.ly/InterviewStatus
Appreciate your help in advance! All the best!!!