Hi @c.soria . The FW for RAK5205 is updated very often. Now it is divided by two parts. One is the bootloader - it includes all basic functionality (deep sleep, tx, rx, etc.) Second one is the Firmware. You ca find them here https://downloads.rakwireless.com/en/LoRa/WisTrio-LoRa-RAK5205/Firmware/
You can modify the firmware via RAK RUI. Please see here https://github.com/RAKWireless/Products_practice_based_on_RUI