Lately I've been thinking to get rid of some old smartphones; among them an Android device and a Blackberry. Not selling or recycling them is the ideal solution, however, I still would like to know how can I minimize the possibility of recovering data from them after the obvious wipe-out/reformat.
So my questions are:
Would it help reformatting the OS multiple times? or is there a way to zero out the memory (not sure if it would be effective as in traditional mechanical hard disks)? and would it help if I fill over and over again their memory with random data (videos, pictures, contacts, etc)?