The iPhone 4-5 was easy. It that fingerprint scanner added a level of complexity that made this engineer squeal “uncle”. Maybe if I had access to a binocular microscope so I could see depth. But at my age, those small pieces are just to small for me to see and work on. And I am just a myopic 55 yr old engineer.
If you replace the same fingerprint scanner into the same iPhone, you have no problems. It's when they were replacing screen/home button combinations where they were running into problems. So long as the fingerprint scanner was still registered to the three other inter-registrable components and was not mismatched, there will be no problem merely disconnecting it and then reconnecting it.
Take it step-by-step and there should be no problems.