To get an even heat distribution at just the right temperature to easily pry the back off I used a steam iron, dry, set between wool and cotton. To hold down the phone I clamped it at the long edges with 2 strips of 1/4” furniture grade plywood cut at 7 degrees, screwed to 2’ 2x6; and then clamped the 2x6 to my work table. This made it much easier to persuade to back off without any oops!
To get an even heat distribution at just the right temperature to easily pry the back off I used a steam iron, dry, set between wool and cotton. To hold down the phone I clamped it at the long edges with 2 strips of 1/4” furniture grade plywood cut at 7 degrees, screwed to 2’ 2x6; and then clamped the 2x6 to my work table. This made it much easier to persuade to back off without any oops!