Otherworldly issues with MicroSD card

[skythefolf]

I have a 400GB sdxc card from SanDisk that refuses to retain any data. (Including the partition table)

 

Windows flat out hates the thing and hangs explorer
(3 separate windows machines, one running AME)

 

Linux sees the card, registers it, detects the correct size of the card, assigns it /dev/mmcblk0 and gives no errors when reading and writing to the disk
(4 separate computers, using different card readers, running arch, debian, Ubuntu, Manjaro, Gentoo, etc. These distros I tried with unmodified kernels, Linux zen, Linux hardened -- only really messed with the kernels in Garuda arch --)

 

What is weird in Linux though is if I write data from /dev/random to the card using dd
(dd if=/dev/random of=/dev/mmcblk0 status=progress)
Allowing dd to run for at least a minute before interrupting it. dd reports no errors, but when I go to read back the data (cat /dev/mmcblk0); all that is returned are zeros.

I also had tried using dd to put the written data back into a file
(dd if=/dev/mmcblk0 of=randomfile)
and using a hex viewer shows only zeros were written to the file, again with no errors from dd

Looking at dmesg also nets nothing, no errors thrown and everything looking normal.

 

I know this card is almost certainly dead but I would like to find out how and why it is damaged and maybe learn a bit about how MicroSD cards work

 

Something else that would be really helpful would be if someone could show me how to enable debugging on the mmc drivers

 

[SimplyGone]

are you sure it's not a fake?

[skythefolf]

2 minutes ago, SimplyChunk said:

are you sure it's not a fake?

Its a legit card, it has worked in the past

[SimplyGone]

Just now, skythefolf said:

Its a legit card, it has worked in the past

Ah ok.  It's just dying then man. don't know enough about them to tell you how to enable debugging.  But i just thought i'd ask about the 'fake' thing cause I've been duped by fake cards in the past