I have thought about this possibility, but I believe the only way it would happen is if the vote count challenge by either campaign on any particular state(s) goes all the way to the Supreme Court, and they decide that there is no way to ascertain if the vote was legitimate and no re-count would fix it. They could give the state the option to re-vote, or to not have their EVs be taken into consideration.
The problem is you can’t invalidate a state’s electoral votes.
The Trump team should take it to the Supreme Court. Show evidence of massive voter fraud. Then tell the Justices that the only way to avoid really bitter partisan divisions that would render the federal government dysfunctional would be to order a re-vote with LOTS of observers and other safeguards present.
If one side loses the re-vote, they can’t claim it lacked democratic legitimacy. They wouldn’t like losing but they would have to admit it was the will of the people.