There’s only one Presidential election in the Constitution. It happens in December since 1936.
There are 538 voters. In 2020, 306 of them voted for Biden (and Harris), and they were elected.
You are quite correct that the correct locations for investigating and protesting were Phoenix, Madison, Lansing, Harrisburg, and Atlanta. There is no one and nothing in Washington DC that had anything to do with any of this.
After extensive debates at the Philadelphia convention, the Founders decided that the States would appoint the President (by appointing Electors), and they rejected any role for the sitting President or for Congress (except on the event of a tie or 3+ way split). The Supreme Court did not come up in the debates (and is not mentioned in the Federalist papers) because the Founders could not have imagined the States united and exercising self-government turning to courts to approve of their self-rule.