USB disconnected and program fail

[mich_x]

I am using nRF 52840 board. I used Keil 5 to load one of the examples in SDK successfully, but when I unplug the USB cable and used the battery. My program doesn't run properly.

The phenomenon is that when connected to PC and click load in keil, LED1 will blink every two seconds. But when using the battery and I turn on the board. The LED1 will blink once and then the four leds will be on in very weak bright.

[KPK]

This happened to me once and I replaced the battery and the problem went away.

[Bjørn Kvaale]

Have you remembered to turn the power switch to VDD instead of USB if you are using a coin cell battery? If you are using a Li-Po battery, turn the switch to Li-Po.