You have to successfully complete the three computer tests to their enhanced standard before doing the MMI interview on the same day.
This is generally true.
However, when I sat my Stage 2 assessments around 3 weeks ago with TPE, there were 6 candidates and only 3 computers available on the day.
So 3 people sat the computer tests, 2 people sat around doing nothing for an hour, and I had my MMI
before I completed any computer tests. It was made clear by the interviewer that I would be sitting the computer tests, regardless of how they thought I'd performed in the MMI.
With regards to the 3 who had sat their computer tests first, they were told how they had performed (all 3 passed, as it turned out), but if any of them had failed then they would have been sent home at this stage, before having their MMI.
Best of luck to you all