I tried booting off sdcard and then immediately installing to eMMC, rebooting, and *then* running upgrades. Now it reboots ok after doing the upgrade on eMMC instead of the sdcard. I can't explain this. I had installed a stretch 5.0.0 nightly a while ago, but it didn't see my NVMe (Samsung 970 EVO). At some point I was booting off sdcard again because the 4.4 installer can see my SSD, then left it alone a few months. when I came back I started over with a fresh 4.4 sdcard image and then the above reported sequence happened.
Furthermore, console=serial in armbianEnv.txt seems to work now. I am perplexed how this could work on eMMC, but not on sdcard. I dont understand how that can be so, but everything is working. Thanks greatly for your help!
smemsh got a reaction from Igor in NanoPC-T4 latest-stable won't boot after initial package update