Here is an excellent site with the Constitution...look at the 20th and 25th Amendments.
It’s pretty clear, Obozo can resign and Biden becomes Pres...OR...the Cabinet and Congross can declare him unable to execute the duties of President...
The former would happen if there was CLEAR evidence Obozo cheated and lied to become President. I don’t think there would be any sort of impeachment unless he dug his heels in...then either impeach or declare unable to execute his duties as President. In “fairness” the DemoRat Congross would elect Biden as Pres and he gets to pick the VP.
In ANY event, the effect would be devastating to the DemonRat Party...for not vetting him, the State Run Media would be guilty of malpractice and Hissy Chrissy would have a tingle running down his leg, all brown and stinky...
...and the GOP would still be SPINELESS, with a pitiful tsk, tsk...
G