To remove the rear case casting carefully loosen the latch on the flexible
circuit connector. These are easily broken so be careful.
Below is the speaker connector with the red and black wire. Remove this connector also.
Take care not to put strain on the flexible circuit (easily torn). Hold the casting apart by only about an inch from the camera during disconnection.

The 7i has an improvement in this area.
The Dimage 7 and 5 have the connector on the back of the camera with the top
flexible circuit making a sharp right angle bend down at the top edge.
I have taken two apart that had failed at the bend (both cameras had to be junked because of this).
Replacement of the top flexible circuit is not practical.