UPDATING FIRMWARE IN nRF52840 USING J-LINK COMMAND PROMPT.

Steps are:
1.Connect J-Link to the PC.
2.Connect target system (nRF52840) to J-Link
3.Start J-Link Commander.
Type the following commands:

J-Link> loadbin <PathToBinFile>, <programmingaddress>

J-Link>loadbin D:\Exe\ble_app.hex, 0x0
Halting CPU for downloading file.
Downloading file [D:\Exe\ble_app.hex]...
J-Link: Flash download: Bank 0 @ 0x00000000: 1 range affected (20480 bytes)
J-Link: Flash download: Total time needed: 0.811s (Prepare: 0.038s, Compare: 0.105s, Erase: 0.423s, Program: 0.218s, Verify: 0.000s, Restore: 0.024s)
O.K.
J-Link>

progamming address is: 0x0

link for reference : 
https://www.segger.com/products/debug-probes/j-link/technology/flash-download/