Good point about the run offs, a la Georgia, but I would imagine that law would have to already be in place at the time of the election that took place. Else, you could have a legislature overturn any election they didn’t agree with, by changing laws, forcing re-votes etc endlessly.
This game will play out by the rules already in place. The key will be getting the right judges (courts) to interpret the rules.
So constitutionally, this goes to the legislature for that state.
The legislature could say they want this done so they can appoint legitimate electoral college voters. That way “every vote is counted.”
The legislature can legislate. SCOTUS would likely have to approve it. However, how could anyone then say that the votes in that county were illegitimate? The legislature gets to punt it back to the voters so they certify the votes in the counties that were not charlie foxtrots and they consider the votes in the county(s) that were.
The remedy for chaotic and illegal voting is clearly spelled out in constitution. No additional law is required to follow the constitution.