But he won in Michigan in 24, so why is he "investigating" that vote?

Because he believes the Democrats cheat, and he wants to prove it. That's what everyone tells him. If he can prove they cheat, then he can punish them the way they deserve. And that will help him gain power, as he gets allies elected in Michigan.

Again, this is not claiming that Trump won't use his powers to try to shape the elections. Of course he will. The entire SAVE Act is itself an effort to use government power (at least through 'normal' channels of modifying election law) to help Republicans get elected more easily.

It's just that this whole idea that Trump has some method that would work by which he could seize absolute power for himself is ludicrous. "Calling out" your "army" of J6 supporters to assassinate both Presidential and both Vice-Presidential candidates (and probably also the Speaker of the House)? That's just ridiculous. What would that even look like? Would he go on national television, speak to camera and say, "Hey, all you J6 folks, go kill the Vice President and Secretary of State and the Governor of California and the fourth one and Hakeem Jeffries, so I can stay President?" How could that possibly be successful?