joekhoobyar

Step 1 - Install the Armbian PGP key and update your APT sources
 
Install armbian.gpg to /usr/share/keyrings/armbian.gpg  (mode 644) You can use a copy from another one of your SBCs, or... ... you can download and install like below (thanks @BrewNinja for the example) touch /usr/share/keyrings/armbian.gpg chmod 644 /usr/share/keyrings/armbian.gpg wget https://apt.armbian.com/armbian.key -O - | gpg --dearmor >/usr/share/keyrings/armbian.gpg  
Edit /etc/apt/sources.list Replace all instances of bullseye with bookworm Edit /etc/apt/sources.list.d/armbian.list deb [signed-by=/usr/share/keyrings/armbian.gpg] http://apt.armbian.com bookworm main bookworm-utils bookworm-desktop
Edit any other files in /etc/apt/sources.list.d as appropriate, to replace bullseye with bookworm
 
Step 2
 
apt update  
Step 3
 
NOTE - WHEN RUNNING THE BELOW COMMANDS, DO NOT ACCEPT ANY INTERACTIVE PROMPTS FOR CHANGING /etc/initramfs-tools/initramfs.conf
The default is not to accept the changes anyway - but I am noting this here to be extra careful I've checked - the changes may differ from what armbian has in the latest images  
apt upgrade --no-new-pkgs apt full-upgrade apt dist-upgrade  

Meanwhile, I managed to do it another way:
- "Boot from eMMC / system on eMMC" via armbian-install -> that creates two partitions on eMMC, one boot, one rootfs
- fdisk, mkfs.ext4 on nvme, rsync all files from rootfs eMMC partition to nvme
- note down UUID of nvme partition from blkid, replace it in /etc/fstab and /boot/armbianEnv.txt, reboot
- nuke rootfs partition on eMMC as it's not used anymore
 
Did you boot from eMMC? You mention no SD card, yet somehow you could run armbian prior to install it; or PXE boot?

At least for legacy kernels, it possible to use Radxa's overlay for the 25W PoE hat.
 
This should allow you to use the PWM fan on the PoE hat.
 
#!/bin/bash # Install linux headers apt-get install -y linux-headers-legacy-rk35xx # Download and compile the device tree overlay h=/usr/src/linux-headers-$(uname -r) wget https://raw.githubusercontent.com/radxa/overlays/f2679399887b678dec62cb50cb44c767a2bcb293/arch/arm64/boot/dts/rockchip/overlays/rock-5b-radxa-25w-poe.dts cpp -nostdinc -I $h/include -I $h/arch -undef -x assembler-with-cpp rock-5b-radxa-25w-poe.dts | dtc -I dts -O dtb -o rock-5b-radxa-25w-poe.dtbo # Install device tree overlay mkdir -p /boot/overlay-user mv rock-5b-radxa-25w-poe.dtbo /boot/overlay-user echo 'user_overlays=rock-5b-radxa-25w-poe' >>/boot/armbianEnv.txt