Fix/reattach the adhesive around the speaker opening.

Add new adhesive as needed to the phone.

Plug in the cable from the fingerprint sensor.

I was unsuccessful at this and accidentally broke the connector. The phone works fine, except it no longer has the fingerprint sensor as a security option.

Press the Back Cover up and then press the back together.

A phone case may help hold the Back Cover in place if the adhesive is problematic.