LEDs not functioning after using external Li-Po battery

[kokheng]

Hi all,

I purchase a Li-Po batter where it will output 4.2V when I connected to nrf52480 DK, it causes all 4 LEDs (LED1, LED2, LED3, LED4) not functioning anymore. 

The Li-Po battery connected to battery connectors P27, please refer to the doc link.

I flash the default dimmer examples to the nrf52480 DK, and it still able to complete the provision and adjust light level without any error return by Android nRF Mesh phone app. 

Everything looks fine for me except the LED do not work.

After that, I tried flashing the blinky example from "nRF5_SDK_15.2.0\examples\peripheral\blinky" to the board and using USB power. Then, the four LEDs still not functioning anymore.  

Do you know what happens on my nrf52480 DK board?

[ketiljo]

Do you measure any voltage on either side of SB9?

[kokheng]

Hi Ketiljo,

IC SC728 (location: U4) is missing on my board, you can refer below picture  

and Nordic doc show it connected to 4 LEDs, it this the reason why the LEDs can't work? do you have any workaround to resolve this issue?

I believe the IC SC728C just stripped out from PCB without any reason because this board was fine previously. Not sure what I did to make it like that. 

https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/nrf52840_DK/hw_buttons_leds.html