[chbot] Unlocking a microSDHC or SDXC card

Volker Kuhlmann list57 at top.geek.nz
Mon Jan 14 05:18:38 GMT 2019


On Mon 14 Jan 2019 15:30:22 NZDT +1300, Trevor Wignall wrote:

> The cards worked for a year or more, then each suddenly stopped working in
> the phone, and the phone no longer offered it. A new card then worked
> perfectly in the phone, so it looks like a software write protect on the
> card, or something else corrupted.

Are you sure this is even possible? There is a small encryption secured
area, but the whole lot?

It looks suspiciously like 2 SD cards with hardware faults to me.

> I don't have any Linux computers other than my Raspberry Pi's, but I will
> try to bring the cards (and adaptors) to the next meeting (in one week's

The RPi will be just fine. Find out which /dev/sdX device appears when
you insert the card. The command is

  dd bs=1M if=/dev/zero of=/dev/sdX

and needs to run as root. On Debbian you need to prepend "su " (no
quotes). Replace sdX as appropriate! For a reliable harakiri on the card
you only need to write the first 512bytes to 2M, the rest just zeroes
leftover file chunks.

WARNING: This will overwrite the whole of the card with no questions
asked. It always works. There is no idiot protection, neither from the
OS nor the system software, so if it doesn't work, you have a hardware
problem. Replace under warranty.

No need for any special blablasoft for formatting that may have all sorts
of loser protection built in...

Happy to help out but I'll be at linuxconf and probably won't have
energy left for other meetings.

Volker

-- 
Volker Kuhlmann
http://volker.top.geek.nz/	Please do not CC list postings to me.



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