If you have an old TV and it presents the handshake problem with green screen you should enable the Force RGB option.
1. Enable SSH connection from the LibreELEC settings on the TV Box
2. Check the IP address of the Box from connection
3. From your computer open Terminal for MAC and Linux or Start - Run - CMD for Windows.
4. Connect to your TV box (user root): ssh [email protected]
This is a MAC command. Check for windows or linux on how to connect via SSH.
5. insert the password: libreelec
7. This starts an editor. Insert the following text:
echo 1 > /sys/class/amhdmitx/amhdmitx0/output_rgb
8. Save with the same name
chmod 755 autostart.sh
Now you have the RGB enabled.
You can check by doing steps 1 to 6 to check if the file was saved.