MSP430FR2475: Regarding MSP430 MCU firmware upgrade

Tool/software:

Hi Team

The Firmware upgrade is done using BSL rocket tool using BSL scripter command line tool through UART.

Can you please suggest for the below case if firmware can be upgraded?

When code / firmware is already running in MSP430-FR-2475 and in between if we connect rocket tool to the connector, Will it enter in BSL mode when we execute the BSL scripter command line or there is other way we have to follow to get into BSL mode like reboot the target MSP430FR2475 MCU or something? 

Can you please guide how this BSL invocation takes place during running the target system?

Thanks

Nitish