I have old cell phones with problems that make them useless (non-responsive touch screen, black-on-black display, will not power up). I also have a bunch of solid-state USB memory devices that don't work (e.g. don't connect). I would like to dispose of this non-functioning junk, but I'm concerned that the devices have solid-state memory devices that contain secret stuff that I don't want unscrupulous people to get ahold of.
There is a recycler that can stick my junk under a degausser (unknown what kind), and can stab my old spinning drives.
The removable SD cards were removed from the phones, but I have no idea what is in the deeper recesses. A factory reset to wipe the device is not an option, and software reformatting is likewise impossible. This leaves me concerned that someone with skills might get ahold of a part and sell my information.
Is the recycler's degaussing procedure likely to obliterate the data (what questions should I ask), and if not is there some other reasonably certain method of keeping the data out of the wrong hands, consistent with recycling (I have some cement, if all else fails)?