Aura H2O Looking for the thread related to copy .img to internal SD

Hi,

I forgot that my Kobo didn't like update because too old.
So I want to burn a .img to the internal memory : `dd if=Kobo_Aura_H2O.img of=/dev/mmcblko`
It appears it didn't work out since no light after reboot or anything.

I remember seeing a thread here explaining in details how to burn an img into a SD.
But I can't figure out where it is.

So if any kind soul would link me the thread in question?

Thanks