I think if Trump can show a major discrepancy, you revote the state.
You either recanvas and look for irregularities like tally sheets not matching voter rolls, tally sheets not matching votes cast (like Michigan was doing with the Stein recount that got halted in 2016), ballots with only Presidential votes and nothing else, multiple rerun ballots, etc., or the legislature declares the vote as irreversibly corrupted and goes to court to appoint the electors directly according to the wishes of the voters as they declare it to be.
-PJ