1. Download Upgrade image
2. Rename the image to spiboot.img
3. Paste 'spiboot.img' into the file system of the first partition on a micro SD card, not on eMMC
4. Power off ODROID-N2
5. Insert the card to ODROID-N2
6. Toggle the boot mode switch to SPI boot mode
7. Power on ODROID-N2
If Petitboot detects 'spiboot.img' from an SD card, Automatically Upgrade itself.
Regarding point number 3, do I paste the image file into a new or blank SD card or with Coreelec installed?
Just as a quick note, If you only have one uSD card, placing the spiboot.img petitboot upgrade file in the CoreELEC partition (the boot partition not the storage partition) of a uSD with CoreELEC on it will work to update petitboot.
So I finally got petitboot to work. First I had to use an older recovery image (20190417) - newer versions did not work for some reason. After the recovery then I followed the streps to update and now I get the petitboot menu in SPI mode where I can choose which OS to boot. @Garcea @cdu13a - Thanks for the info. I used a new SD card but it’s good to know I could have used the CoreElec card.