I have similar problem here. I have a Slice box with the original CM1 and Slice OS mounted.
I would like to upgrade the OS to LibreELEC. I tried to manually update the OS, but current LibreELEC-Slice.arm-8.2.3.tar files from the Download section are broken links. Than I tried to flash the eMMC storage following the instructions on the Raspberry Pi foundation website. Unfortunally, after having installed the driver, when attaching the Slice box to the micro USB, Windows 10 said that new hardware is not recognized and I don't know how to proceed. Any suggest?