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I have a few SD cards that appears to be write protected with some advanced method and I do not manage to write on it nor reformat it.
I have tried with all the usual methods I could find, but nothing works. I post here the testdisk log of
Analyse > Quick Search > Deeper Search > Delete (clear MBR partition) > MBR Code
I always get a "Write Error" message.
Anyone has seen a situation like this? Thanks for your time and help.

Some SD card have a manual switch that you can use to write protect them.
If it's not the case and you are unable to write to them, it's usually that their electronic is damaged.

well... yes, I also tried switching the write-protect switch
The electronic is fine. The cards have been used on a device (POS) that somehow locks them for writing on any other device (the device writes them and can modify the files, the files are visible and readable on a computer) but unfortunately there is no way to delete the files nor to format the card. I tried on Linux, Windows, OSx with several partitioning tools with no result. I always get some sort of write error message. That's why I am trying with a sophisticated utility like TestDisk. Could the warning message about the geometry point me in some direction? Unfortunately when I try to change the geometry with TestDisk I also get a write error message.