Sorry, had to edit that... I was thinking of the A64 when I wrote that, where SD has priority over eMMC, but on the RK3399 in the PBP it's SPI -> EMMC -> SD, so you're basically in a pickle and having to either play with the disable switch, remove the eMMC and put it into a eMMC USB adapter and re-write it, or play with maskboot recovery mode (requiring an specific USB to USB cable)... not for the faint of heart!
I know on the RockPro64 there was a SPI bootloader that made it so SD had priority over eMMC (and also allowed usb and even PXE boot) but I don't know what the state of affairs for that is on the PBP. That would basically make it unbrickable though, as you'd always have SD boot priority.
I know on the RockPro64 there was a SPI bootloader that made it so SD had priority over eMMC (and also allowed usb and even PXE boot) but I don't know what the state of affairs for that is on the PBP. That would basically make it unbrickable though, as you'd always have SD boot priority.