Thinking like a villain
The best way to prevent crime is to figure out how crime happens, and then taking measures to prevent it from happening.
So, if I were to steal a phone, lets say an S 5 for example, as I was walking away from the scene of the crime, I would either turn the phone off, or take the back off and remove the battery. Then I would remove the SIM card, or whatever the phone has. Replace battery, leave phone off.
Create new ebay acct with false info, sell, delete account as soon as money is deposited, and collect money. Let the buyer deal.
So, how can we prevent this?
Glue the back of your case on, and never go in public.