nRF Device Firmware Update APP
The firmware should be in .zip file format, prepared using nRF Util (https://github.com/NordicSemiconductor/pc-nrfutil). The firmware can be selected from the local storage on the Android device or downloaded from cloud using a deep-link (see https://github.com/NordicSemiconductor/Android-DFU-Library/#deep-links for details).
Note: The app can't be used to update firmware developed with the nRF Connect SDK. In that case then the nRF Connect Device Manager mobile app must be used.