[STM32G031] (8 pins) upgrade firmware [STM32Cube Programmer] & UART , boot mode

[Lola_]

Hello, I'm trying to enter the boot mode of STM32G031 with SW.

the STM32G031 is connected to the STM32F4 board through UART communication and I can only set the BOOT0 pin high when connected to STM32F4' GPIO. 
as the RM0444 section 2.5 indicates, the boot configuration includes the BOOT_LOCK, nBOOT1, nBOOT0, and nBOOT_SEL bits. 

is there a possible way to enter the boot mode of the STM32G031 when it's connected to another board? 

[TDK]

Generally, yes. If the default option bits are set, holding BOOT0 high during reset will enter the bootloader. If you can't control the NRST pin or power, then the only method to get into the bootloader is to jump there in software.

[Lola_]

I do have access to NRST pin 

[TDK]

Toggling BOOT0 without resetting the chip won't do anything.

Program your code to jump to the bootloader upon receipt of a signal or message.

https://community.st.com/t5/stm32-mcus/how-to-jump-to-system-bootloader-from-application-code-on-stm32/ta-p/49424