BACKGROUND I formatted a mini SD card with FAT filesystem, placed some files on it. Placed into a kids toy (Landzo) and when I removed the card the whole SD was marked as read-only by the firmware of the toy. I tried a million of the most common things and I don't seem to be able to make the card RW again.
PROBLEM I can't format the card nor edit its content. I want to format and as a bonus, it would be awesome to know what the heck goes on... It's a mini SD so there's no pin to flip on the physical device.
WHAT I KNOW
This is what the structure looks like

WHAT I TRIED
I tried to change the permissions (chown) on the card since the info card shows that it is read only. No errors but also no change. I tried on the volume and the disk. Didn't do anything.

Then I tried
sudo diskutil eraseVolume exFAT MYSD MBRFormat /dev/disk2s1
I tried volume and then the disk option and I received back the same annoying error:
Couldn’t open device. : (-69877)
When I tried other exoteric things I received back the consistent error that the car is not writeable.
It's a mini sd there's no switch, the table/partition has been modified and clearly, it is fooling the standard commands. I am OK in losing all content, I just want a way to gain back the card for further tries on what I was trying to do in the first place :-)
I also tried from windows with Diskpart which went a little further and also on a Ubuntu machine. Nada!!!
Tried another zillion of things based on an extensive search on StackOverflow and other venues. I am at a loss...
Help!