The Supreme Court very nearly stepped in, you’ll remember that Alito told Pennsylvania to keep the challenged votes separated, but Roberts won out, wanting to stay out of the politics. Separation of powers.
The way it would go, and it has happened several times before, is the votes from the states that cannot be certified, get thrown out, and if no one gets enough electoral votes to win, it gets sent to Congress to make the decision. Each state gets one vote.