You can find the 2-1 opinion and dissent at this link. I’m at a meeting so no chance to read this closely right now, but it appears that the majority held that many of the ballots cast by challenged voters failed to comply with North Carolina law (such as by not including information on registration forms like the last four of a social security number or drivers’ license number), but would give 15 days for a cure. This kind of remedy, in an election decided by fewer than 1,000 votes could well lead to both a scramble and an outcome determinative change.
The dissent is lengthy but says early the key point: “Changing the rules by which these lawful voters took part in our electoral process after the election to discard their otherwise valid votes in an attempt to alter the outcome of only one race among many on the ballot is directly counter to law, equity, and the Constitution.” Voters voted under rules set by the election administrators, and to disenfranchise them after the fact violates those voters’ due process rights.
There are a few things that may happen now. There may be an appeal to the state Supreme Court, where with Justice Riggs (who is one of the candidates) recusing herself, this case could lead to a 3-3 split with the appeals court ruling standing.
There also may be a revival of the Fourth Circuit federal case—to me this has remedies of Roe v. Alabama, where a state court appeared to violate due process in changing the rules for a state election after the fact. The state courts may be violating federal law by disenfranchising voters in this way.
If this process does go forward, I don’t have a good sense as to what it would mean for a 15-day scramble to try to un-disenfranchise these voters.