How to rework microSD card? MicroSD card is write-protected and can not format

Windows shows the microSD card is write-protected. Data can still be read from this Patriot card, but no writes will work. If you open the explorer and delete the files, it looks like the deletes worked, but if you take the card out and put it back in, the files are still there. Likewise, if you copy files to the microSD card and replace the card or restart the computer, the new files are no where to be found. The card will also fail to format.

The manufacturer tells me to send the card in for them to replace, but I can not send it because it has source code on it. Manufacturers just don't understand that RMAs can not be done for storage devices with sensitive data that can still be retrieved. Instead the manufacturer says that they will take the card back to "rework" it, so it sounds like this problem can be fixed. Can the end user do it?

This is a microSD card so there is no LOCK switch.

I have tried the following things and nothing works.
1. SD formatter
2. Registry changes
3. Partition changes with diskpart
4. Active Killdisk

Does anyone know how to fix this problem?

This message was edited 1 time. Last update was at 03/08/2016 21:42:47

According to the Sandisk web site, "Write protection errors occur when a flash drive detects a potential fault within itself." This means the microSD card detected an issue with possible memory corruption so it disabled writes, so the microSD card goes into "write-protected" mode. This sounds similar to a Linux file system when it automatically remounts the disk in read-only mode when it sees an issue with the disk.

There is a video entilted "Exploration and Exploitation of an SD Memory Card" which describes how a SD memory card typically works. They mention that it has an ARM-based microcontroller in addition to the flash memory whose job is to manage the memory and write data only to the good blocks. Think of it as a mini-CPU that controls where data is to be written. In the video the researchers got the card to run code. As a result, it is possible to send a few commands to the mini-CPU to clear the write-protect status or maybe request it to rebuild the bad block table.

Unless you have specialized hardware or software, you probably won't be able to "rework" or repair the microSD card.

References:
- Sandisk
- Even tiny microSD cards have chips that can be hacked