Remove back cover.

Shove the sim card remover or blunt (not sharp!) metal object into the hole that is inside the sim card slot. There is a specific hole that appears to designed to allow you push the back cover off with a small metal rod.

The leather back seems very fragile. It folded and bent easily so peel back with extreme caution and go slowly.

It might not be obvious from the pictures, but the black "lattice" on the inside of the cover is the adhesive. It must be pried loose (carefully!) for the back to come off.