Hi,
I'm in a similar situation. I have an Iphone Xs that is completely broken, the front part, the back part, the microphone does not work and the rear camera does not work either due to water infiltration. However the Iphone still works and I use it every day but sooner or later I know it will stop working. My question here is the following: I also have another Iphone Xs in the drawer that is in immaculate condition but is blocked by icloud. Can I change my broken iphone's motherboard and face id to my new iphone and still keep everything as it was? If yes, what ifixit toolkit do you recommend?