See this interesting item from Post #9 ...
If a state thinks it's in risk of defaulting on its Electoral College participation, then the legislature can exercise its plenary power to call a special session and choose to directly appoint their Electors, regardless of how the state's citizens voted.
This should give us a bit of comfort. The states where your scenario -- a swing state with a Democrat governor and/or Secretary of State either openly rigs the election or refuses to certify the state's results -- is most likely to unfold are the following:
Pennsylvania
Michigan
Wisconsin
North Carolina
I'm pretty sure all of these states have Republican-dominated state legislatures.
In the scenario we're discussing, the will of the voter is unknown due to the systemic chaos created by the Democrat party.
Even if the will of the voter were known and the legislature tried to overturn it, they'd be on solid Constitutional ground to do so given that their power to choose the method doesn't have a "no backsies" clause; their power to choose is Supreme law of the Land, and their legislation to choose the method is subordinate to their power to choose.
Politically, they'd have a harder time justifying their own reelection if they overturned the vote of the people. However, they'd be in the right if they stopped a prolonged uncertainty that was rife with fraud and lack of confidence in the outcome.
-PJ