The only remedy I see is: SCOTUS could rule a state’s election violated the equal protection clause. Due to fraud, not all legit voters or candidates were treated equally under the law. Therefore, the previous state election would be ruled invalid and it would be up to the legislature of each violating state to determine either: hold another statewide election, or as a legislative body, vote among themselves for their electors. The “remedy” therefore, would be left to the state legislative branch, who is held responsible constitutionally for choosing their electors.
Worth repeating