Problems installing - can't mount SD/read-only

I'm following this guide to install LibreELEC on my Mini MX: LibreELEC

I create the SD card (tested using both Rufus and win32diskimager), and everything seems fine. I can access the files and write to the drive (the dtb.img file) fine in windows.

I insert the SD into the box, and hold the reset button while inserting power, but it just gets stuck on the teddybear that says Welcome. If I remove the SD I can get to the menu.

So I tried the alternative method of loading the update zip onto the SD, and manually select it from the box, but when I did that I got lots of errors about mounting and read only. However it said LibreELEC was successfully installed.

But now it won't boot at all. Just stuck at the teddybear with or without SD inserted/reboot held down.

I tried making a new bootstick, this time a USB drive, but I can't get past the teddybear.

Anyone have any suggestions?

Quote from kostaman

What did you do about using a Device tree ?
Your Box is what ? MiniMx 1gb / 8gb ?
You must have missed a step along the way as the MiniMx should run on LE.

This is the exact device I have, 1GB version: ** URL removed **

Yes, I downloaded gxbb_p200_2G_beelink_minimxIII.dtb and renamed to dtb.img and placed it in root after writing LibreELEC-S905.aarch64-7.0.2.007.img.gz to the SD card using Rufus.

Anyway, as mentioned, now I'm unable to enter the boot menu in any way, just stuck on the Welcome screen.

But if I get able to enter the boot menu, is it not possible to just copy LibreELEC-S905.aarch64-7.0.2.007-update.zip to a USB and use the boot menu to write it? In that case, what about dtb.img?