To rotate the screen on your Steam Deck when booting into LibreELEC, you can try the following steps:
Boot into LibreELEC on your Steam Deck.
Open the Terminal app.
Type the following command and press Enter:
xrandr -o left
This should rotate the screen 90 degrees counterclockwise.
If the screen is still not oriented correctly, you can try other rotation options by using the following commands:
xrandr -o right (rotates the screen 90 degrees clockwise)
xrandr -o inverted (rotates the screen 180 degrees)
xrandr -o normal (restores the screen to its default orientation)
Once you have found the correct orientation, you can save the settings by creating a configuration file. To do this, type the following command and press Enter:
sudo nano /etc/X11/xorg.conf.d/10-screen.conf
This will open the Nano text editor.
In the text editor, paste the following lines:
Section "Screen"
Identifier "Screen0"
Option "Rotate" "left"
EndSection
Replace left with the correct orientation option for your setup (e.g., right, inverted, or normal).
Press Ctrl+O to save the file, then press Ctrl+X to exit the editor.
Reboot your Steam Deck to apply the new settings.
After following these steps, your Steam Deck should boot into LibreELEC with the screen rotated to the correct orientation.