The described steps are intended for the device, as it leaves the factory, multi-boot is not activated in the factory firmware, you activated it yourself. You have already changed the state of your device (activating multi-boot changes the contents of eMMC and SPI, and changes the entire logic of starting systems from external media, not allowing you to start systems with a new format). In fact, the primary "activation\inclusion of multi-boot" is the transfer of the "old" (which does not know how to launch new systems from external media) version of u-boot to SPI. Until multiloading is fixed to work with new launch formats, multiloading needs to be disabled. I have already written to the Firefly developers what needs to be fixed in the multiload so that it works with all systems (with new and old formats). The correction is simple (just a few lines), but so far there is no answer from them.