At the barest minimum, you'd need the Supreme Court to endorse such a move, and that's just not going to happen. A state reversing/decertifying electors in between the time they are certified and the Electoral College vote would be a different question. But once the EC is voted, it seems no different than would a member of Congress deciding a month after a bill passed that he should have voted differently, and expecting that to repeal the law after it was already signed.
The Electors have voted, and one state deciding after the fact that it changed it's mind isn't going to change that.
But once the EC is voted, it seems no different than would a member of Congress deciding a month after a bill passed that he should have voted differently, and expecting that to repeal the law after it was already signed. I think a better analogy might be where, after the bill passed, that member of Congress's election was invalidated for some reason. I think in that case, any Supreme Court would apply the de facto officer doctrine and hold that the law is valid, as other courts have done in similar challenges to laws by state legislatures. Any other result would be chaos. It would do the same with the vote of an elector if it was determined, after the fact, that the elector's appointment was invalid.