Did you activate nvidia drivers?
You can do this from another PC, that is on the same network as your PC running batocera and with a tool like WinSCP for example.
user = root
password = linux
You have to edit the file "recalbox-boot.conf" which is in the directory /boot
Just remove the "#" in in the front of the line "#nvidia-driver=true". Then save and reboot.
To be able to edit the file you first have to open terminal and enter this:
mount -o remount,rw /boot
Or alternatively install the hard disk (on which Batocera is installed on) into another PC or connect it to another PC via USB in an external housing (or with a SATA to USB-Adapter) and edit the file "recalbox-boot.conf" in the root directory.