You can find the Court’s order, a concurring opinion, and two dissenting opinions, at this link.
The court’s three liberals were joined by conservative Justice Hagedorn in holding that the exclusive remedy for an election contest is to start in the a lower court that can take evidence. (This is not the first time that Justice Hagedorn has sided with liberals in an important voting case).
Chief Justice Roggensack, dissenting along with Justice Ziegler, would have had the Court take the case and have the trial court work to collect evidence for the Court’s benefit. But the Chief Justice added the following key language:
If [the Wisconsin Election Commission] has been giving advice contrary to statute, those acts do not make the advice lawful. WEC must follow the law. We, as the law declaring court, owe it to the public to declare whether WEC’s advice is incorrect. However, doing so does not necessarily lead to striking absentee ballots that were cast by following incorrect WEC advice. The remedy Petitioners seek may be out of reach for a number of reasons.
Justice Rebecca Bradley issued a separate dissent (joined by the other two dissenters) that did not express a view on this question.
It is possible that Trump tries to file a case now in the lower court, and that it could conceivably make its way back to the Wisconsin Supreme Court. But with time being very short before safe harbor day and before the electors meet, there may not be time. And there appears to be a majority that believes there would be serious impediments to overturning the results of an election based upon supposed legal errors committed by the WEC that are not at all the fault of Wisconsin voters. (Among those impediments is laches; a challenge to the means for dealing with absentee ballots should have come well before the election.)