I could be wrong (I'm no lawyer :blushing
but it sounds like a panel of federal judges agreed with the California Supreme Court in the Ayala case and denied Habeas Corpus relief. In another words, they refused to hear the case at the 9th Circuit court level. Since they were denied Habeaus Corpus relief, they appealed to the Federal Supreme Court and the decision was overturned at the Federal Supreme Court level.
This would be similar to when Brendan first appealed to the 7th circuit. The judges could have denied his petition for Habeas Corpus relief and thus the 3 panel judge would not have heard the case. But that didn't happen. Brendan's petition for Habeaus Corpus was granted and the 3 panel judge's ruled in his favor. (unlke in trial courts, cases in appellate courts always ultimately are heard before more than one appellate judge-usually in set groups ("panels") of three or more judges.) The state didn't like that decision and appealed to the whole 7th circuit (en blanc) and IIRC~~at least 1/2 of the judges (qualified and non-disqualified judges) have to agree to take the case (note 3 had to accept his original petition for Habeas Corpus relief) Since at least 1/2 of the judges on the 7th Circuit granted Wisconsin's petition to take the case, oral arguments will take place in September 2017. The Court will have time to make a decision~~(hopefully in Brendan's favor). If they don't rule in his favor, then Brendan can petition the Supreme Court to hear his case. I believe 4 of the 9 Supreme Court justices have to agree to hear the case.
Zellner stated in early July, 2017 that she doubted the Supreme Court would take up the case. I don't know if her opinion has changed since then. If that is the case, then this en blanc hearing is a really important decision for Brendan and I don't expect a decision to be made before then end of the year. I'm guessing sometime early 2018 for a decision on the en blanc.