Not able to power up nRF52840 using a battery pack

[sprasad]

I successfully ran the proximity_demo supplied by Nordic. I used my laptop's usb port to power up the device and it worked fine.

Then I unplugged my laptop and tried to connect the battery pack to the board. The LED5 blinks rapidly and the board switches off after 10secs approx.

Again, everything works well with my laptop usb port. Can anyone point out what mistake I'm doing here?

btw here is the battery pack I'm using 

https://www.amazon.de/Kinps-10000mAh-Portable-Externer-Intelligent-10000-Wei%C3%9F/dp/B01M0309EM/ref=sr_1_1?ie=UTF8&qid=1518799040&sr=8-1&keywords=kinps+powerbank+10000

[Edvin]

I think David's theory sounds very plausible. 

LED5 is connected to the programming chip. I don't know exactly what triggers the flickering in your case, but it could be logging information (UART). You can choose to only power the nRF using SW6, which will not power the programming chip. This means that none of the leds or buttons on the board is connected, but you will still be able to use the radio, and connect to it via e.g. nRF Connect.