Recently I used my host machine to flash my jetson xavier nx developer kit in order to give PPS support to jetson.
However, I followed the instruction from: Enabling PPS on Jetson Nano and then flash the kernel of Jetson, when I finished flashing. My Jetson could not boot. The log of flashing shows: The target t186ref has been flashed successfully. ***
Reset the board to boot from internal eMMC.
Besides. I flashed my machine with: Jetpack 5.0.1
Do you mean JetPack version 5.0.1? There is no available version 5.1 yet (and 5.0.1 is still considered a developer preview).
Btw, a full serial console log would be useful (I can’t personally help on A/B redundancy, but anyone who does will want the full boot log). When you have a screenshot it only shows a small part, but the same serial console app has the ability to save the entire boot to a log file, and you can upload the log file to this forum.