Nothing can be permanently written to microSD card

[arg0r]

Hello, I'm having trouble with a SanDisk Ultra 64GB microSD card, which seems to have a hardware issue(?) where no written data stays on it after it loses power. I am apparently not the only person who has experienced this with this particular card.

Examples:
Snapped picture with phone. Rebooted. Picture gone.
Deleted everything in Windows. Took card out and put back in reader. Everything's back.
Did a full format. Took card out and put back in reader. Again, everything's back.

I have actually RMA'd the card, but I don't want to send it with my private data (no, not what you're thinking). Is there a way to erase it?

 

[jimpz]

Does your phone actually support a 64gb card? (Some only support up to 16 or 32gb cards)

 

[arg0r]

Does your phone actually support a 64gb card? (Some only support up to 16 or 32gb cards)

It does, it's a Galaxy S4. And whether the phone supports the card or not is irrelevant as far as I can tell, since I tried to do things with it in Windows and any added/modified/deleted files would just revert (to the way it was before changing anything) after re-inserting it. Plus, the card has worked since I bought it almost 1,5 years ago, until a week or two ago.

 

[jimpz]

What may be the issue, The phones specs say it supports a micro SDHC up to 64 GB, your card is an ULTRA micro SDHC, small difference, but one that has caused issues in other hardware, I believe these are supposed to be faster & some hardware has problems w/ this.

 

[arg0r]

Indeed, the S4 does not support UHS speeds, but the microSD should work fine since those cards are downwards compatible and will work at class 10 rates on non-UHS-compliant hardware.

Nevertheless, the reason of the problem isn't what I'm looking for; I'm trying to figure out how to get rid of all data (preferably a full format) so I can send the card to SanDisk

Edit: After a little searching, I've found out that the S4 is known for frying cards. So you could be right that it's the phone's fault.