Deleting (Erasing) all Data from Failed SanDisk MicroSD Card

I've had two 32GB SanDisk MicroSD cards go bad recently. One I was able to temporarily revive using the kind advice offered in this thread: Recover Data from Card that cannot be read

When I insert the other into a reader, it registers as 30.6MB (that's MB, not GB).

I've tried all sorts of software and other techniques to revive this card and retrieve the important data off of it (including FindAndMount and TestDisk). Nothing has worked.

So I'm thinking of returning the card for a refund.

But first, I would like to make it unreadable by someone more skilled than myself. Is there any way to do this, given that I cannot even format the card or get it to be recognized as more than 30.6MB?

I am looking for a method that does not entail the kind of obvious physical destruction that would jeopardize obtaining a refund from the retailer. If Costco (where the card was purchased) accepts physically destroyed cards for return, then physical destruction is acceptable (but please have knowledge that they do).

Given two failures, I don't really want to send the card to SanDisk for replacement, because I no longer trust the reliability of their products.

Solution 1:

I'm not sure if an SD card cut in half would qualify for a refund/replacement. A more gentle way is to use a piezoelectric element from an old cigarette lighter. Click it a couple of times on each pin of the SD card, then put the card back to the card reader to verify its death. Repeat if the card is still detected.

Solution 2:

Run DISKPART from the Run menu or a command prompt. Use list disk to show the available disks. You should see the SD card listed. Pay attention to the size reported. If it shows the full size of the drive, then continue. If it only shows 30MB, then be warned, this procedure is not likely to erase the whole card, and physical destruction may be your only alternative to be certain that it is unreadable.

Continuing on with DISKPART: use select disk # where # is the number of your SD card's drive. If you aren't sure which one is your SD card, use list partition after selecting the disk to see if it looks like the right one. Run list disk again to verify that the selected disk now has a * by it.

Once you are awake, sober, and sure that this is the right disk, use clean all to zero out all the bytes on the selected disk. Once completed, type exit to exit DISKPART.

It is possible that the card's hardware is fine and the partition table just got toasted. You can try reformatting the card and doing a chkdsk /r to test all sectors.