Reduce power consumption on booting?

I used to power jetson nano from micro-usb port but after while this port stoped working and the power led is not working anymore so i switched to barrel jack , however , it’s started for while then shuts down . i know that when powering jetson from barrel jack we need 5v,4A power supply , my power supply is 5v , 3A power bank . is there a way to reduce power consumption to work with my power bank

You may try using 10W with NVP mode 1 rather 15W with NVP mode 0 with:
sudo nvpmodel -m 1

You would also check that your barrel jack has the EXACT dimension.

Otherwise you may check if your Nano would be RMA-able…

i can’t login to the nano because i see only the logo of nvidia then the nano turns off.
is there a file that could be modified in the sd card image to change the mode from 0 to 1 ?

Not sure for recent releases, but you may try to adjust PM_CONFIG DEFAULT in /etc/nvpmodel.conf.

That being said, if your nano is not able to boot, I’m afraid it will be very limited.

Note that failing to boot is often not an issue of total power availability so much as it is an issue of needing closer regulation (e.g., tiny voltage changes over a very short period of time will often cause shutdown even if the average output of the supply seems sufficient).

i tried two different power sources ( power bank , and adjustable power supply) both provide (3A) but both of them gave same result

Did you try another powerful supply to log in and change the nvpmodel?