You are already aware of the voluminous eyewitness testimony that you cannot refute.
He is already aware of a lot of the other evidence that I've already shown him too. He just wants to deny it exists.
Evidence like:
* Videos of illegal activity in election offices.
* Changing of laws ex-post facto during an election.
* Violating Constitutional procedures and Congress in conducting an election.
* 'Counting' while election offices are closed with NO OBSERVERS, and videos of the same.
* Mathematical improbability of all votes arriving overnight being for Biden.
* Size of Biden vs size of Trump rallies before the election.
* Failure to maintain security of ballots.
* Demonstrated faults in Smartmatic and Dominion voting machines.
* More people registered to vote in several counties than are of voting age in the population.
...and of course, the current one you are discussing...
* Sworn affidavits from both Republican and Democrat election workers testifying of election fraud occurring in the offices they were working.
and,
Too many States that never chose their electors.