Arduino not working without the USB cable

Hello,

This is my first post here!!

So, i have this problem. My Arduino Nano is not working on external power, it is only working when i plug in the Usb cable.

If i power the Nano on external power the L led flashes and the servos do not move.

Even with a 9V battery the Nano prefers to work only with the Usb cable plugged in.

What can i do to make it work without the Usb cable attached?

if you have USB to ttl device just check where your code get struck.

check power consumption by servo!!! what is specified power you use to turn on nano board