when I power up the 4 GB Jetson Nano using Barrel Jack Power adapter (5V 4 A), it works fine, but if the power get disconnected (from the source) and come back, the Nano doesn’t power up automatically unless I unplug and plug back the barrel jack again.
So, even if I have the barrel jack power is connected to the Nano, and I plug the adapter to the wall, it will not work, unless the Barrel Jack power physically unplugged and plugged back in.
This seems the adapter has some left power, can you try another adapter or DC supply? Or can you measure the voltage of barrel jack to check the voltage level difference b/w your two operations?