nRF51822 device firmware update (dfu)

Hi, all
Does anyone know how to update firmware for nRF51822?
I recently bought a watchX but it looks like have an old version of device firmware or does not have it.
Because I tried to download an nRF51 example of callbacks, but it gave an error that I need to device firmware update.
Also, I tried to download an nRF51 example of at command, but it gave an error that the factory reset function is not working.
Please help me how to solve this situation.

I used the Adafruit Bluefruit App to connect und update the BLE Module.
Get it from Apple or Google App Store.

But sorry this is only to update the pre-installed Adafruit Firmware.

Thanks for your help.