ERROR: You have the experimental desktop GL driver enabled.

To recover from such a situation, there are 2 options:

• Get the SD card out from the Raspberry PI and insert it into a Windows/Linux system. You'll have access to the boot partition, where you can find the config.txt file used to enable the OpenGL driver. Edit this file and comment/remove the line containing

    dtoverlay=vc4-fkms-v3d
  

  Insert the SD card back into your RetroPie system and start the system, without the OpenGL driver enabled.

• Access your system via SSH and run raspi-config again to disable the OpenGL driver, then reboot the RetroPie system.
  Note: If you haven't previously enabled SSH access to the system, then use the instructions to enable SSH on a headless Raspbian system from the Raspbian site:

  For headless setup, SSH can be enabled by placing a file named ssh, without any extension, onto the boot partition of the SD card from another computer. When the Pi boots, it looks for the ssh file. If it is found, SSH is enabled and the file is deleted. The content of the file does not matter; it could contain text, or nothing at all.

  If you have loaded Raspbian onto a blank SD card, you will have two partitions. The first one, which is the smaller one, is the boot partition. Place the file into this one.