MECOOL bb2 pro 3gb

Hi , I have been trying to flash CoreELEC onto a "Mecool BB2pro 3gb) am using generic arm version of 9.0.0 from your list , after burning it to an SD card , i then go into the device trees folder and copy the correct image for my box , however there is already a dtb.img file on the card after burnibf the gx to it , so i deleted that and replaced it wth the image from the device tree folder and renamed it dtb.img but using either the power off box insert sd card and re connect power whilst hoding in the on/off button nothing happens , same when using the terminal emulator app on the box , screen shows black background and Me cool logo, I have to remove the sd card and reboot box to get android to boot again ?am I doing anything wrong ?

Please name the dtb.img you refer to as correct image. ??

Verify specs below:
Model: BB2 PRO
RAM Type: DDR4
Ethernet: 1000M

CPU: Amlogic S912
GPU: ARM Mali-T820MP3

Thanks for replying , I was wondering if I was doing the correct thing by deleting the dbt.img that is already on the card ( after using rufus ) and replacing it with the renamed image was the correct process , as there is no mention of there being a dbt.img already on the card in the "how to " guide.
I haven’t got the packaging that came with the box , looking in settings- “about media box” there’s only limited info , android version 6.0.2 , kernel - 3.14.29 , build - number - BB2 PRO-userdebug 6.0.1 MHC19J 20170114.121107.V0923 test-keys,serial number - D07658088B4E0,
in "memory " it says "total memory 3.00GB "
internal storage - 16GB
I remember when i purchased it , it was 3gb model.
device tree I used - gxm-q201_3g_1gb

Update , i changed device tree to the one without 1gb at end and it has worked thank you for helping.