Is there a way to load the Bx600 Breakout Boards with central role device firmware (BL620)?

Answer

The Bx600 Breakout Boards are intended for peripheral mode, BL600 firmware, only. The latest BL600 1.8.88.0 firmware supports UART Bootloader and all future firmware upgrades are done via UART. Unfortunately, BL620 firmware does NOT support UART Bootloader because the version of the Nordic softdevice used in the BL620 firmware doesn't support it. Therefore, BL620 firmware can only be loaded with a JLink. The Bx600 boards do not have a JTAG interface and are therefore designed for peripheral mode (BL600) only. For the central role side we recommend either the  BL620-US USB Dongle or the DVK-BL600.  The DVK-BL600 has a JTAG interface which supports switching between the BL600 and BL620 firmware, as well as the following additional hardware: a temperature sensor, voltage measurement circuit, programmable LED array and push button switches.