White House after his term is up.
He can't rig an election because he wouldn't be on the ballot.
If he tries to stay in the White House, the new election winner becomes the power and can have Trump removed.
The only possible way is for Congress to change the 22 Amendment, but it would take 2/3 of the vote to do that. That will never happen.
How Hitler did it is there was a flaw in their constitution where in an emergency you can take civil rights away. We don't have that flaw in our constitution.