When using the Odroid-N2 install file, CoreELEC usually correctly identifies if you have either the ODROID-N2 or ODROID-N2Plus and then uses the right dtb for your device. There are however a few situations were this might not be the case. Booting with Petitboot is one such situation. Petitboot may refuse to boot your CoreELEC install.
[note: The issue with petitboot not being able to boot the 9.2.4 release of CoreELEC has been solved. petitboot needs to be updated to at least version 20200806 which can be found here: https://forum.odroid.com/viewtopic.php?p=302140#p302140]
This can be fixed by manually selecting the correct dtb for your device.
There are two easy ways this can be done.
Method #1 - uSD or eMMC attached to computer.
Attach uSD or eMMC to your computer and mount the CoreELEC partition.
You will find a directory named device-trees if you have mounted the correct partition.
In this directory you will find 4 dtb files related to the N2 and N2Plus.
For the ODROID-N2 copy the following to the root directory of the partition and rename it dtb.img
g12b_s922x_odroid_n2.dtb
For the ODROID-N2Plus copy the following to the root directory of the partition and rename it dtb.img
g12b_s922x_odroid_n2plus.dtb
(Note: the two dtb files which have dvb in their name are only for people attaching certain internal DVB adapter to the gpio on their device.)
Make sure to safely unmount / eject your uSD card or eMMC module.
Reattach uSD card or eMMC module to your device.
Method #2 - Using ssh
Instructions for the ODROID-N2Plus:
mount -o remount,rw /flash
cp /flash/device-trees/g12b_s922x_odroid_n2plus.dtb /flash/dtb.img
sync
mount -o remount,ro /flash
reboot
Instructions for the ODROID-N2:
mount -o remount,rw /flash
cp /flash/device-trees/g12b_s922x_odroid_n2.dtb /flash/dtb.img
sync
mount -o remount,ro /flash
reboot
You can verify that you are using the correct dtb by going to
Settings > System Information > Hardware
If the Hardware: line says the correct model name of your device then you are all good.