I see. This is unexpected (also unexpected that the above didn't say
/dev/mmcblk1: No such file or device ...
So please run
sudo dd if=/dev/zero of=/dev/mmcblk0 bs=1024k count=50
sudo dd if=/dev/zero of=/dev/mmcblk0boot0 bs=1024k count=50
sudo dd if=/dev/zero of=/dev/mmcblk0boot1 bs=1024k count=50
sudo dd if=/dev/zero of=/dev/mmcblk0p1 bs=1024k count=50
one of them may fail (please let me know which), but that'll be fine. Once you are done, the board may become unresponsive: just unplug, put the SD card in and reboot.
Just to provide context: what we are trying to do is to make the eMMC unbootable, so that the board will just boot from the SD card, so we want to write zeros to the beginning of the boot partition. This was supposed to be
/dev/mmcblk1p1, hence writing to
/dev/mmcblk1 (as per the wiki) should erase that whole filesystem. However, it looks like it on your board it is on
/dev/mmcblk0p1, hence the commands above.
no problem. I guess we will update the wiki after this.