Not much; what I've done before is drilled through the flash to quickly get the job done when someone asked me to deal with these phones or I need to get rid of one myself; it doesn't wipe out the contents, but it makes it impossible to recover. I usually go through the board, not just the flash. GENERALLY, I do one large hole and physically hammer the flash chip to be sure.
At that point (depending on who I did it for; me or someone I know, or a client), I handle it case by case:
- Personal device: Heh, it can wait
- Good friend: I warn them I will not burn the gas for one phone (NOTE: I can and do make exceptions for data-sensitive devices, I'm not that insensitive but no I'm not wasting gas on a personal phone with zero recovery chance) that day, but if I know I need something or I need to go somewhere NEAR a BB or other store who I can verify takes them I'll let them go with me if they need transportation. If I'm going to pick up something I grabbed as a pickup like an R10 for example I'll work with you at that point, then you can hand the phone in.
- This isn't to be rude, and I've ALWAYS been clear about this; gas is too expensive enough of the time to casually drive you to BB for a phone that is physically unrecoverable. Using it to grab a new toy is different.
- Client: It gets done (different situation; they come first). If I have others, the client's phone goes in the pile.
That said, once you do the dirty part put the board back in the phone. Don't make the person taking it explain why there's a hole in the board. They don't need to know. If you can open it to drill it you can put it back together.
Take a picture of the board so we can see where the NAND flash is.
-- should be under here on the metal shield. On the black sticker phone, peel it up and see if you can't tell by feel.
This is how it should be done. For context this is a router from the Draft N era (~2007) I was asked to drill through for disposal. Absolutely not needed but the person who asked me to deal with it wanted to be sure. Normally I'd fight back a bit and reset it but Draft N is dead and almost none of the specs made it into the final N spec. Draft routers are very often DOA; this one ran a super early revision and was DOA when finalized.