The fastest and easiest way of preparing a Libreelec/Openelec Sdcard is to use the Libreelec USB/SDcard creator. You can download it here.
Afer installing the SDcrad creator, Run it.
It should show like the image below
In Here you should:
1- Select your device and the version you wish to download from the Libreelec server.
2- Click "download" to start downloading the version you selected on step nº1
Or you can "select a file" you might have already downloaded to your hard drive.
3-After you plug in you Sdcard to you PC it should be listed here automatically.
4-Click "Write" to start your SDcard writing process.
Once it is finished you just need to remove your SDcard from your PC and plug it into your WeTek device.
Power it up and press the power key on your remote (while pointing directly at the WeTek device) when asked by the on-screen message.
Libreelec/Openelec should be running perfectly.