great to hear that there is simpler solution
Well, the first thing is to access the serial console. You have to google how to do it as I don't have this G-box. Do You have the box from that link: Geektech - GBox Midnight 2.1 UART (Serial Connection) ? if jest You would need to solder wires to serial console pads. And then connect the serial to usb adapter to it.
First: I'm sure I've seen already somewhere the solution for that (but can't find it now). Try to find this answer.
Second: If You will not find the answer I could guide You how to do that. But You need access to serial console of the board, and You will need to change some u-boot environment variable. Basically I need You to paste here the output of the "printenv" command from the u-boot console. Do You know how to do that ?
So it is my understanding that when libreelec is installed, it installs the core components to the NAND flash of the device, and then upon first boot it sets the device storage to external flash (USB formatted with the proper filesystem) to use in the future.
Where You read this ? I can tell You that I put LibreELEC-Amlogic_G02REF.arm-9.0-devel-20190307225115-0e98e15.img.gz onto sd card and booted the box with it. Libreelec installed on the sd card and did not touch the nand. I can dual boot, when sd card is inserted the libreelec is booted and whithout sd card the stock android rom is booted from nand.
I have different request if I may I'm using device with dvb-t tuner si2168, and it is not detected in this build. It is however working on the stock android rom. Is it possible to add driver for this tuner ?