ya know that episode of Stargate SG-1 where they try to surgically remove the goa'uld from Major Charles Kawalsky but they miss a tiny bit and it just takes control of him and kills him? that's basically trying to reinstall any piece of Microsoft software in a nutshell
never mind if the software is as simple as an installer and it's problems are as silly as a corrupted download cache, it absolutely will not ever let you restore it to a base/clean configuration under any circumstances, it will fight you to the death and it will win