Which Box is it? How to find a flashfile?

You can write the AMLGX "box" image to an SD card (no flashing to internal storage, we don't support that) and experiment with different dtb names in uEnv.ini (edit the dtb to use, don't rename the dtb files). I can't really recommend a specific dtb to try; perhaps VIM1 since this has a complete dtb with features like Broadcom WiFi/BT enabled. The boot log shows the box has BL2 secure firmware, but that just means we need to exclude some additional memory areas (and we do, else we use them and crash the secure world OS). It's 1GB device so I would have low expectations for overall performance. LE images should support the keyboard without any issues. If you meant the remote, you will need to put it on the network and SSH in then follow https://wiki.libreelec.tv/configuration/…figuration-hard

We don't need to break the secure OS, only avoid it, since it's running long before LE/Linux gets started. LE should work with the vendor u-boot and the normal Amlogic recovery boot process. NB: If your goal is to run Armbian you're in the wrong forum. I don't run it often and am not that familiar with it (someone else's problem, so to speak).