Great! That worked. Thanks much for the help – I think I’d tried flashing u-boot previously but might have had on old u-boot.bin.sd.bin on my machine from last year. I’m now able to get it booted.
The next issue I see (which again I never faced with my last unit): no HDMI. If I boot with an HDMI display attached, I see the pre-kernel log messages on the display, but I never see the desktop appear. Looking through the u-boot log messages, I noticed that u-boot was failing to parse the device tree:
Found /extlinux/extlinux.conf
Retrieving file: /extlinux/extlinux.conf
1: kernel-5.10.69-12-amlogic-g98700611d064
Retrieving file: /initrd.img-5.10.69-12-amlogic-g98700611d064
Retrieving file: /vmlinuz-5.10.69-12-amlogic-g98700611d064
append: earlyprintk console=ttyAML0,115200 console=tty1 rw rootfstype=ext4 init=/sbin/init rootwait swiotlb=1 coherent_pool=1m root=UUID=730575af-8654-46cc-a99d-231c6837336d
Retrieving file: /dtbs/5.10.69-12-amlogic-g98700611d064/amlogic/amlogic/meson-g12a-radxa-zero.dtb
** Unable to read file /dtbs/5.10.69-12-amlogic-g98700611d064/amlogic/amlogic/meson-g12a-radxa-zero.dtb **
After some digging through the forums, I found this comment that suggests removing /boot/extlinux completely, to force u-boot to use uEnv.txt instead. I did that, and now seem to be able to boot properly with no errors in u-boot and HDMI working. I’m confused why I never had this issue with my last unit, on which I installed the exact same OS release. Does the /boot/extlinux/extlinux.conf file get installed as part of the u-boot reflash? If so, it seems like something that needs to be fixed so avoid this manual workaround.
In any case, I’m going to continue setting this unit up the same way as my last one and see if I run into any additional issues.