The platform can be configured to enter a BIOS update (download and execute mode) when UART2_TXD (pin 78 on connector J6) is pulled low—and held low until the de-assertion of PMIC_RESET_N.
Additional requirements for the DnX sequence to function:
A USB device female port, for example a micro receptacle on USB2 port 0 or the Type-C port
Route +VBUS from the USB connector to the module +VBUS signal (connector J6 pin 99), this allows the module to detect a host connection and mount the media.
A properly formatted source media with a valid BIOS image in the default partition.