I have investigated further and it turns out that not all GPIO pins work for this function. For GPIO pins 16 and 17, the function bootloader_common_check_long_hold_gpio_level in bootloader_start.c always reads HIGH level, even when I have verified with a multimeter that the pin reads 0V. I even put ...

I'm having the same problem - I have tried with GPIO 16 and 17 - bridged the GPIO to Gnd. The bootloader ignores it, both when resetting via the reset button on the board and by power cycling. In the confiuration I have set: [*] GPIO triggers factory reset (17) Number of the GPIO input for factory r...